He has participated. Would be no different than a player transferring after playing last season. If it is determined the transfer is for athletic reasons (which this one would clearly be) then he will be ineligible. I can't see any DEC ruling him eligible. No matter if he establishes residency.
Also, the word I am getting on this situation is this young man has got the wrong people in his ear telling him he doesn't have to go by the team rules. They had some issues last season. Not a team player. Thinks he is above the team and should be treated special. He came in this season with the attitude that you can't win without me so therefore treat me that way.
Brenham will never sign off on him and whatever district he transfers to (if he does) that DEC will not rule him eligible.
I will say, if he were to transfer, his best bet would be with Navasota. It's possible that the two Fort Bend schools (Crawford and Willowridge) along with Stafford, could vote in his favor just to keep the opportunities open for themselves when transfers come their way. He would need to transfer now so that DEC can make the ruling. Next year a different DEC could be in play with realignment.