Since Assassin's Creed Unity takes place in the midst of the French Revolution, poverty is rampant amongst the citizens of the game, and running across a beggar is pretty common. Luckily, Ubisoft included an option to toss money to these poor souls...the problem is that that money needs to be picked up.
So when an assassin runs across a limbless beggar and tosses some money at the ground, the beggar is pretty much the only person who this DOESN'T help. Really, it's just teasing the poor handless man. That's Templar behavior, Arno. Tsk tsk.