I have used Free Download Manager for a long time and have never found a problem with it.
FDM supports BitTorrent, so the person on TBB might have downloaded a torrent which FDM may simply be seeding? I've also asked this question in the linked thread on TBB.
I personally wouldn't panic and uninstall it based on one isolated issue that probably has a rational explanation. It just seems a little odd. Like I say, in my experience it's never caused me any problems at all!