This is objectively a good move for Phil.
He is joining a promotion (in still a relatively strong viewership) where he has no pressure, starts every Dynamite and will be given time to get back his form in front of fans.
I guarantee you, after a year or two of getting his form back the WWE will be begging for him to join them.

He is basically replicating Hogans late career path (WCW -> minor promotion -> Back to WWE)