Yes, you're right, and Antony really found a great environment at Real Betis, which made him very eager to join this La Liga club. He even said that he rejected an offer from Bayern Munich because he only wanted to go to Real Betis. Wow, he was on loan at Betis last season for a few months and has found his home.
Even if he chooses Bayern Munich, it is not certain that he will play as a main player because Bayern Munich already has good players, he might only be used as a reserve option which means the same fate as at Manchester United so choosing Real Betis is the right choice because he will be a main player for the team and he is also not in a team that is full of pressure. Real Betis is usually just an average team that is not bad and not too good but at least it is better than a weak team that is around the relegation zone.
Antony claims that he had an offer from Bayern Munich but chose Real Betis, no source mentions the transfer rumours, I don't think Bayern Munich need Antony because they have Olise, and Antony is not better than Olise in every position; Antony is just an average player who people believe has the potential to become one of the best players. I don't see Antony as a big player because he had a good performance at Ajax and Manchester United signed him, but I haven't seen any good performances that helped the team he played for, he scored goals for Real Betis last season but couldn't help them in the Europa Conference League final against Chelsea.
Antony chose Real Betis because the team did not have players who are better than him, the only player that is helping Real Betis is Isco, and since he got injured, Real Betis' performance has looked very poor, Real Betis signed Antony on a permanent deal and they are expecting a good performance from him because of what he did last season. Antony should simply focus on his new squad and perform well because if he does not do well, he will not enjoy what the fans will do to him because La Liga teams are not patient.