Morbit really doesn't need to eat. I mentioned before that it can photosynthesise and survive on that quite handily. Somebody also claimed it as a pet, once, and named it Morbit. That's useful, because otherwise it wouldn't have a name, although that character is since deadtimed.
So Morbit probably won't eat the whole troll, not least because it's still alive. Morbit, despite being a hunter and predator, actually prefers not to kill unnecessarily- live food has the most life energy and therefore the most information available to copy; Morbit can't get anything from a skeleton, and next to nothing from a body over a month old, even if it's frozen. The same goes if it's been prepared. Freddy might notice that Morbit gets bigger from the troll than it did from the meat- more life energy is absorbed from what is eaten, so Morbit gets bigger.
Morbit will probably stop after gaining everything it thinks of worth from the troll, but can't gain something twice from the same source (Morbit's feathers are chicken feathers, so it can't copy chicken feathers again; but Morbit could replace them with eagle feathers, after which Morbit can copy chicken feathers again). Speaking of, do the tentacles actually do anything, are they unique to this troll, and are they hereditary? Is there anything unusual about the troll's internal anatomy (second liver, enlarged spleen, complex heart, etc?)