I would at least want him arrested, but I'm with you on a lenient punishment.
I mean, we can always buy another rooster...
I'd was his arse severely beaten until he thought he was going to die.
When I was in the 82nd I was a member of the White Falcons, 2/325th. (Long time ago.) Well, they took away our white falcon mascot, (live falcon), because of some endangered species crap. So our battalion commander got us a white gamecock to replace it ... we called it Foghorn. We'd take him to the field with us, he'd jump out of airplanes with us in a kit bag. Damn rooster had about 500 jumps because he was jumping with every squad, every platoon, every company in the entire battalion.
He was always under guard by the battalion CQ at night, tethered to our flag pole. But one night this idiot from another battalion got drunk and managed to steel our rooster and he rang his neck and plucked him out behind Charlie Company's barracks.
Well, he was caught in the act and before the MPs could arrive he was beaten half to death ... busted jaw, concussion, cracked ribs, lost some teeth.
He had it coming for being a dick head.
You gotta protect what's yours.
It's up to whatever the taterheads want to do to that kid that busted up that rock - that's their call. But if someone stole and killed Sir Big Spur, there would be hell to pay IMHO.