What you are saying certainly make sense.
However, like I said before, Shilao is ONLY credible because he is not a fully independent actor/person. The price he has to pay for knowing more about the real PLA, is that he is also subject to security restrictions and is held accountable for what he says. This is also why someone as logical and attentive to detail as you would "believe" what he says. Because what he says could be considered a credible source with a level of confidence deemed sufficient by you. However, from the POV of the PLA and Chinese authorities, Shilao's words are also credible and thus have the risk of leaking important technical details of the PLA's abilities. Therefore, just like
@asif iqbal won't get his pictures, you won't get Shilao's words.
Your original words: "But telling us that the PLA has some more capable and sophisticated A2G capabilities that we haven't seen, is not particularly useful." should be enough to explain my point. The PLA will NOT give the general public information that some like you can determine to be "useful", because if you can determine it to be "useful", than a professional spy would at least dig even more sensitive information from those.