I feel the naivety is strong with this one...
There's a difference between blindly accepting what Chinese state media says and critically considering the potential validity of what they are saying.
In this case, you're skeptical regarding the statement of the operational deployment of two AShBM systems, in other words, you are skeptical regarding an official statement regarding military capabilities.
From past experience and examples, we know that Chinese state media has sometimes either allowed personalities to make incorrect statements of military capability, or maybe repeated incorrect statements from foreign media.
However, it is typically rare for them to publish independent statements directly from the Chinese military itself, especially when it is regarding important military systems. The statements about J-XX/J-20 back in 2009 from air force general He Weirong was an excellent example of state media getting it right on a very important weapons system. In this case, the statements were made during an important military parade for an important anniversary so there is a good likelihood that the information was provided from the military itself.
So based on our collective experience about the kinds of statements state media makes about various weapons systems-, it is worth considering the possibility that this particular statement may be true.
Then we should see if there is any collaborating evidence and logic that may support the idea that their statements are true.
In terms of evidence for DF-21D and DF-26, it is simultaneously both limited and vast. Obviously in the same way as all other Chinese weapons systems, we never have any true "independent" verification of any Chinese military activities or developments. However, there are certain trends that we can acknowledge as indicative of various things. For instance, the deployment of various weapons systems during military parades are an accepted indication that those weapons systems are operationally deployed for some meaningful amount of time, and well beyond early operation, testing, and development stages. That is why we did not see J-10B, GX6, J-20 or Y-20 there this year, because they are all in varying stages prior to being operationally deployed. Therefore by that logic, the fact that DF-26 and DF-21D are present, suggests that they have been operationally deployed for some duration, or at the very least are beyond the operational testing stage.
In terms of logic, the idea that DF-21D is an AShBM is generally accepted. We have also known about the existence of DF-26 as an IRBM for quite a few years now, and there is no reason why DF-26 cannot be adapted to an AShBM (or even be developed from the outset to be a dual IRBM/AShBM missile). So the idea of DF-26 being an AShBM is not a stretch of the imagination.
Whether DF-21D and DF-26 are operational or not, is another statement worth looking at. Above, I have said that the presence of weapons systems at military parades tend to reflect their operational nature. If we further examine the circumstances of the statement being announced I think we will find that they are realistic. As said before, state media statements about military matters are not always reliable, however some instances of greater reliability may occur if they are made by reliable individuals, or perhaps during "sensitive" occasions, such as military parades/anniversaries given the gravity of those occasions.
Finally, it is worth remembering that Chinese state media rarely "exaggerate" the capabilities of the Chinese military. They are not north korea, Iran, or even Russia. More often than not, they keep silent regarding new weapons developments until those weapons are well into advanced development or in operational service. Many times the statements that they make regarding new advances may be late. Sometimes state media will even go out of its way to dampen down popular expectations of a weapons system in discussion (such as 055). This shows a consistent pattern of mostly making statements that are the "minimum" of actual capability at the time, rather than seeking to exaggerate reality.
There are strong real-world effects of this policy, which I won't discuss here, but for the purposes of our discussion, it means that many state media statements about military capabilities and advances (depending on the circumstances of a statement being made, and who is making the statement) can be considered to be reliable.
Certainly in the case of DF-21D and DF-26, there is no reason to believe the military would allow state media would lie about their operational status, given lying would be exaggerating their military capability (which is rare for Chinese state media on military matters), and it would also be unexpected for them to lie during something as important as the 70th anniversary VJ day parade.
You can challenge just what "operational" means in- Chinese military parlance, i.e.: what level of capability it provides, however that is a few levels deeper than what is being discussed.
So, you should use words like naivete a little more carefully, I think. If we are watching the PLA, we should always maintain a degree of skepticism but we also need to be logical in assessing new statements, and in this case, I think most people would consider the statements to fulfill many criteria for being reliable.
And given plawolf's posting history I think it's not a stretch of the imagination to think he has gone through the proper logical hoops to come to his conclusion.