The problem with Punk is that he's already a hugely divisive figure, just from his past behaviour and general outspoken demeanour. The casuals are still into him, but the kind of people who frequent reddit and other social media, not so much. WWE hardcores never totally forgave him for trashing the company when he left. AEW hardcores never forgave him for the way he left that company. Punk fans would staunchly defend him because they felt aligned with his generally progressive and rebellious attitude - even when he came back to WWE, it was largely excused with "it's a different company now that Vince is gone" or "a guy's gotta work" - as if Triple H doesn't have plenty of Vince's shitty habits and Punk hasn't already made more money than the majority of people will make in ten lifetimes.
However even Punk supporters are struggling to defend him for this. It makes them look stupid for belieiving in him as a person, not just a character. You either have to accept it was always a character and a brand designed to make money - or that the guy has changed as he's gotten older and simply sold out. Either way, increasingly difficult to defend him, so now Punk has WWE hardcores, AEW hardcores and a lot of his sizable former fans shitting on him collectively. It's brutal but ultimately a rod he's made for his own back. You can't loudly proclaim yourself as being 'the voice of the voiceless' and some kind of anti-establishment rebel for decades and then not expect massive backlash when it turns out at best it was just a phase, and at worst it was a straight up sham to get people to buy into a fake character (granted that is kinda what wrestling is, lol, but still... Punk's popularity and success is as much due to people appreciating Phil Brooks the man as CM Punk the wrestling character).
I imagine some in AEW are looking over with a wry smile at what's happening. Punk didn't need the money, so I don't think it was ever about that. He wanted and got his WM main event (albeit not for a title) but seemingly at the price of having his identity eviscerated both nationally and internationally. Cena's promo cut deep because it wasn't just a heel talking shit - he made a lot of totally valid and unarguable points about Punk being a total hypocrite, and that was without mentioning AEW at all. Then Punk has to grovel and apologise to Saudi Arabia - which then gets broadcast on Smackdown for the crowd. Feels like that Vince-era pettiness returning. Triple H playing the long-game and Punk paying the price for selling out his morals.
Feels like the only route to go down with Punk is to lean into the sellout thing and have a Corporate Punk type character. That actually could be quite fun - particularly if he teamed up with Cena (think the two man power trip from back in the day with Austin and Triple H). I don't think it'll go that way, but if you're going to humiliate Punk on TV, you might as well adapt his character to a role that benefits from it.