It's definitely not a dehumanization because in the fantasy genre orcs can produce fertile offsprings with humans.
This is the scientific standard for being the same specie. The classic scientific counter-example is a mule, the cross of a donkey and a horse, because mules cannot produce offsprings. So mules, donkeys, and horses are not the same specie.
However, I still think it's probably too far for this site.
The Ukrainians refer to Russian soldiers as "orcs" because they exhibited complete disregard for the Geneva Conventions and even more basic rules of war, even going as far as executing POWs.
But it's still a term which is not inherently descriptive. It clearly attaches a negative sentiment. So in a collegiate discourse it should not be used.
I am not sure about calling the Russian soldiers "the Horde" though. An argument can be made that the Russian empire was created by a breakaway province of the Horde, which appropriated the legacy of the Kievan Rus to gain legitimacy and then expanded to gain most of the Horde's territory. Certainly the Moscovy Province inherited its administrative and military traditions more from the Horde than from the Kievan Rus. And its initial period of expansion was Eastward, into the Horde territory.
So, the other practice, of calling the Russian soldiers "the Horde," while derogatory, may also be descriptive as an allusion to a certain view of history.