I'm new here, just stumbled across the site. I don't think the quotation is authentic, but I do enjoy composing maxims as idiomatically as I can, and my Latin version of Maximus' statement is this:
Mors nos adridet omnes, homo nil agere potest quam eam adridere.
Another good line in the film, one that many people seem to have missed, is "What we do in life, echoes in eternity." My version:
Id quod per vitam agimus per aevum reboabit.