If he kicks off with a tiny force, then he spends a long time floating back down. So the pipe keeps on moving backwards slowly for a long time. In the end, the distance (velocity * time) is the same and it's all back where it started.

yes but if there are other people climbing up the ladder , the
tiny force that he applies will be overcome by the larger forces.

so if you have 1 person stopping at the end and 20 climbing
and 20 floating back.

20 larger forces -------------------->
and 1 tiny force <-
and 1 person stopping<--

so you have the force applied by 20 people
vs the -force of 1 person as he reaches the end plus the tiny force he applies to return , and the tiny force cancels out when he gets there.
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.