the photo isn't good for judgeing becuase the rein is too tight, so he must flex to there. I know, I know, U said not to critique your bro.
Anyway, Was he trained western orginally.? Did they do the thing where all they want is for the horse to flex at the poll, (the more the better) and do the yank, snap, yank, snap to keep reminding him to keep it there? If so, then he is rewarded when he puts his head in that "behind the bit" position. This is hard to untrain. Much easier to train a stargazer to come down than a rolltight to unroll. When they come behind the bit like that , you lose control.
Start riding him on really loose contact when you can , however, when you do ask him to stop (and use your seat and voice as much as possible), do not release him if all he does is roll his head up and stay leaned onto his front legs. Ask him to actually back up and lift his head and give in his whole body, not just break at the neck and still be leaning forward. When he lifts his head, even it it's to toss it, and gives with his whole body (shoulder raise, he steps vigourously back and you feel him rock back onto his haunches) you DROP the reins to his neck . . total release.
This and training him to reach downward and forward at the walk. I actually have my horse trained to reach down if I kind of tickle the rein and say, "Down". He loves it.
Four is really young and for him to go all scrunched up like this for a long time is really detrimental to his physcial development. I hope you will bag the showing for awhile and work on getting him happy , forward and stretched out.