Symbolism, Imagery, Allegory
Thidwick's antlers represent Thidwick… in that they do not represent Thidwick. Confused? What we're trying to get at here is that the antlers represent Thidwick's objectification. But hang with us, and we'll unpack this so it's crystal clear.
Objectif-what?
Objectification is a philosophical term and a killer Scrabble word if you can manage it on a triple-word score. Good luck with that, though.
As for the philosophy part, the Stanford Encyclopedia of Philosophy defines the term as "seeing and/or treating a person, usually a woman, as an object." The "usually a woman" part stems from the fact that the term came into prominence within feminist theory, and if you've seen a Sports Illustrated Swimsuit Edition cover, you know exactly why that is. Ladies can have brains for days, but on the cover of that magazine, they are reduced to bodies. And in this reduction, they are treated like objects—hence the term objectification.
As identified by Martha Nussbaum, and later Rae Langton, there are ten features to objectifying someone. These include reduction to body (seeing someone only through their body parts), instrumentality (treating someone like a tool), ownership (treating someone as though you or another person own them), and denial of autonomy (treating people as though they lack free will).
If this is all starting to sound like a moose you know and love, then kudos to you. A certain motley crew of critters objectifies Thidwick in spades.
Ain't Nothing But a Thing
Thidwick's antlers represent the animals' objectification of this big-hearted guy. Seeing only the antlers, and treating them as a thing instead of a part of a whole being, the freeloaders don't consider Thidwick to be equal to them. They don't believe he has feelings or thoughts—what we might call agency—worth considering.
Consider this very telling scene:
He stepped in the water. Then, oh! What a fuss!
"STOP!" screamed his guests. "You can't do this to us!
These horns are our home and you've no right to take
Our home to the far distant side of the lake!" (29.1-4)
For starters, those horns aren't just an accessory Thidwick sports because they are fashionable that season—they are a part of Thidwick. Heck, physically they are Thidwick. But the animals only see the antlers as their home, as an object for their own use. But they aren't just objectifying the antlers when they call them a home; they are objectifying Thidwick himself.
And as an object, Thidwick's needs don't factor into their thoughts about how things should go. So when he tries to get the moose-moss on the south side of the lake, the critters don't consider that a very good idea.
Objectification is part of the reason the freeloaders are so very unkind to that most kind moose. They don't see him as a creature, but instead as a thing. And who cares if you're kind to a thing or not? It's not like it has feelings. Oh wait…