It could have gone down that way possibly.
I was basing it off of what was said about Shawn fighting for cross play. If there was a power struggle in general, and cross play wasn't going to happen if he couldn't get his way, if he is the type of person who has to have full control or nothing, or is contemplating retiring or moving on anyway, maybe both, he could have made a deal to have cross play become the norm across the platform, in exchange for his leaving and getting out of the way peacefully. Assuming cross play wouldn't be seen as a major loss to the business, and only a minor one, if at all of course. It could always be revoked when PS5 launches, and only remains on PS4 if the new leadership doesn't really want it, however they try to spin how and why they couldn't or wouldn't do it for next gen.
This would allow him to go out on a high note on his part, even though it's not something PS would really want to explain to the public. It's the kind of thing we would find out in an interview 10 years down the road, like how they opened up about PS3 and it's troubles after all these years. It would partially explain these news events coming out so close together, and the lack of explanation as to Shawn's departure.
Sorry but doesn't make much sense. He is a very high level corporate, so his contract and business ethics would already prevent him from bad mouthing Sony on the terms of his resignation. Don't see why they would have a truce proposition of "if you do what I'm asking for I'll leave the company".
I'm not saying he would try and smear PS, I'm saying if he was starting to hate his job because of the internal conflicts, and it didn't look like he had enough power or control to get his way in terms of what he wanted to implement, he could have decided to leave since he may be thinking it anyway, while getting something he wanted implemented in return for his departure.
I've been part of companies who've done some weird, odd, or downright stupid things before, just to clear up power struggles and major disagreements in management.
I could be wrong though, just figured it may be a possibility.