In this case it isn't even a guarantee that anyone has to die as the problem is presented, the tram can just continue to be passed along. The default setting for the lever is "go to next" so to not pull the lever is easier both physically and morally.

The individual that pulls the lever is the same individual that would take action to harm others for no benefit, and even in real life I can't morally take responsibility for a person who runs over a child by purpose after I let his/her car merge in front of me just before a school crossing