As per https://community.sdl.com/product-groups/translationproductivity/f/90/t/9437, trailing whitespaces are automatically removed when segments are stored in a TM, but there are instances in which those "extra" spaces are needed (Worldserver projects, for example).
What about adding an option in "File - Options - Editor - Automation" with anything like "Remove trailing whitespaces when updating TM"? It could also be added to "Project Settings", sure. :)
Cheers,
David