Sounds like it's a food thing...

Once he's out, he relaxes and doesn't try defending himself but when he's in his enclosure, he's striking at any heat signature, r.e. your hand, but not the hook without a heat signature!?!?!

My breeding female is mad for food at the moment, had struck at the heat signature of my hand once this week, and even last night after she smashed a medium. Her feeding response is so acute right now, when I checked on all my fed BP's a few hours later to make sure they had eaten, she swiftly came out of her hide, where she was ambush ready and struck at the glass where I held the torch close to it.

Unsure of your location, but where I live, temperatures are dropping and humidity is rising (slightly - usually fairly humid in the UK anyway) and this can influence their eating habits, especially as they get older.

Just guesstimating here, but at circa. 1 year old, he could quite happily take a smaller sized weaner but maybe he'd like to try his chances on a larger sized weaner if he's grown on enough?!

To finish, you've already been offered some great advice by some very experienced handlers here and ones I am actively trying to learn from daily so no doubt you're in the right place to help you and your little dude live his best life.

Good luck