So far you people are not counting up the odds here. According to Cosimo, Harry is suppose to accept his new surroundings and he will then die on Voyager and then carry out this time stream which is some fairy land to what end? To accept he's dead? Cosimo said he had been doing these experiments for awhile and it's a 50 to one shot the victim will just blend-in to the situaltion.
That's not how it is with Harry though who decides to do something that is very technically difficult and daring and that is to steal a shuttle and go back to entry point.
No doubt the experiment is-- the time stream will merge with real time and Tom will disappear (he must be expendable) and Harry will marry Libby.
Why glorify Tom if he is the only original character that must be killed?