Plus there's the fact there aren't that many JH7 to go around. PLANAF JH7 are mostly there to do antishipping missions, which is a pretty crucial mission. So PLAAF's JH7 would likely have to be used. Chinese air forces have a rather low number of dedicated strike planes with crews training for strike roles. Makes more sense to give the AAM to various Flanker platforms. Heck, even J10 platforms make some sense. While they could carry probably fewer missiles - there are many more of them to go around. And sensor wise, J10A are probably not really behind JH7. J10C is probably ahead in sensor department.
While there's a worldwide push towards networked weapons - the air force as a system still benefits from more platforms having decent sensors being in the air - such formations will more easily create an image of the battlefield, than having a mix of platforms with good sensors and platforms like JH7, which are suited better to being simple trucks to actually carry the payloads. J16 (and theoretical modified J11B) are the best platforms for the new AAM. There are a lot of them (with modified J11B included), they have good sensors, they can carry as many missiles as JH7, their crews have been trained for interception missions more than JH7 crews and they have better acceleration/speed than JH7.
Now, the question, in my mind, isn't at all whether the big missile carried by J16 is an AAM. It probably is. And the missile seen under the JH7 may indeed be an identical missile. An AAM. But there still might be a possibility that PLA is developing added variants of the missile. Such a large missile is perfect as a basis for added variants. We've seen other missiles, which started of as AAMs, to at least entertain the idea of added variants. AIM9 was tested an air to ground missile. Chinese makers promoted SD-10 in an antiradar variant. Meteor missile has recently gotten a mention from BAE about the possibility of an SEAD variant. And so on...
Well I think the question I would ask is why we think it is unlikely for the JH-7/A to receive an VLRAAM payload in the first place?
Fundamentally, if we all accept that the maximum range of this VLRAAM can only be exploited through CeC-esque capability which even more advanced aircraft like J-16 will have to rely on to use PL-X, then what reason is there to doubt that a JH-7/A may be an inappropriate platform for PL-X?
After all the way I see it is that the benefit of PL-X and its reliance on CeC is that its maximum capability can be exploited without requiring the launch platform itself to have any kind of sophisticated fire control system, but only that it requires the plane have a sophisticated datalinking capability.
From that point of view, IMO the entire concept of PL-X should have been suspected to be a weapon that may be potentially much more widely fielded beyond J-16, but potentially all combat aircraft capable of physically interfacing with the missile -- other Flankers, JH-7/As, maybe even H-6s and J-10s.
Looking specifically at JH-7/As -- they are a very attractive combat aircraft family after the Flanker family to receive this missile, considering JH-7/As size means it will be able to carry a respectable number of PL-Xs while still retaining capable range and endurance.
In fact I would argue that J-10s make less sense to carry PL-X than JH-7/As, because of that exact reason above.
In fact, you describe the JH-7/A as being "simple trucks suited to carry loads" -- which I actually fully agree with and it is why I think the idea of it being a PL-X carrier makes sense. PL-X theoretically shouldn't require the carrier aircraft to have sophisiticated sensors of its own, but rather it can rely on the rest of the friendly force's networked sensor capability and just lob missiles to where those friendly sensors and networks directs it to.
In a way a JH-7/A carrying PL-X is not too different to being the aerial version of its air to ground missile truck role that it already has.
