Engineer
Major
I don't doubt the PLAAF could find a use for a J-31. It would seem the natural conclusion to replace aging J-10s with J-31s for a 5th generation hi-lo mix (any such turnover would of course by years away). However, I think the "rumour" that this project is entirely self funded by SAC is indicative of the PLAAF's current interests. I'm not entirely sure the PLAAF is ready to commit to two fifth generation platforms. At the same time, the PLAN is fully expected to have a growing appetite for new fighters as it develops a carrier capable force. Given the ambiguity of potential buyers, it would simply be good business practice for SAC to mitigate risk and appeal to as broad an audience as possible.
It is precisely because PLAAF isn't going to equip the 310 that SAC needs to think outside of the box, such as selling the plane as an aggressor unit instead of a normal operational fighter.