As today is Columbus Day in the U.S. I have seen a lot of use of the word genocide in relation to the enslavement and death of the indigenous population of the Americas. Genocide is a fairly modern term are people applying it to events like Columbus guilty of presentism?
Just because it is a modern term does not at all mean that it only applies to modern affairs.
Genocide is the purposeful destruction (not necessarily violent) of a certain people or culture, and there are many events throughout history that can be considered that. The Holocaust is the most obvious example due to it's systematic and clear-cut mission of destroying both Jewish lives and culture.
The result of Columbus' and Europe's conquest of the Americas could definitely be considered genocide, but I won't argue either way as that is not what you are asking.
So no, it is not a presentist argument to call past events a genocide provided they meet the definition - was the aim of a war, conquest or act to rid the world of a certain demographic? If so, you have a genocide.
I'll argue that no, because genocide implies a systematic and purposeful destruction of a people (stolen from /u/vivalastone). And that was not how Columbus viewed the natives.
Deaths from Columbus's expedition, for the most part, were due to disease.
Death on Columbus's behalf was usually from working the natives too hard, or punishing them to harshly.
He was not out to get them. He needed them dearly for labour. If one was looking to reap the financial rewards from a labour force one wouldn't kill the labour force.
Read his account (which is partly Las Casas's, aka the violence is likely exaggerated) and what his son wrote on his expedition.