Really? Why is the original/classic trolley problem in any way interesting if the future weight of the decision on the human has no bearing? (That's a serious question.)

In the problem statement, an actor has control over whether this 1 person or those 5 people die. If they choose red, then 1. If they choose blue, then 5. (Failing to make a choice is choosing blue.) If after playing the scenario, they knew someone would use a Men In Black pen on them to completely forget what happened, is there a rational argument against choosing red?

(I realize this might read like trolling, but I genuinely don't find the original problem a difficult one if you eliminate the human guilt aspect.)