Is there anything stopping him from having the same opinion as before? He plays football then goes home. He's not a political figure. Did he ever stand up and say he will lead LGBTQ rights? Or was he just supporting and had a few statements that people liked? Will him playing there means he is no longer allowed to say he supports the cause?
I get it, people are upset because they thought he'd be some big leader for the cause. But ultimately, moral/opinion wise, he can have the same opinions as he ever does. From his personal POV, he's retiring from elite level football and getting a big pay day to play casually over there. That's about it. His decision to live where he wants, doesn't mean it affects his opinion. It doesn't make you anti LGBTQ if you live somewhere, and as a result are then paid by someone.
Just like if Qatar takes over United, it doesn't make us anti LGBTQ if we still support the club the same as before. I'd prefer they don't take over, but it's not changing my support as I don't need to support the causes of my club/company/employer. And just like I have my own opinions/beliefs that everyone should be free to do as they like, it doesn't mean that I'm gonna actively go to LGBTQ freedom rallies. You can have an opinion without having to protest for it every day of your life.