But furries have nothing to do with sexual content no more or less then normal human society.
You could also say the few thousand million of inner sphere people never wanked off at all but tell me how many NSFW books did you see get published or special abilities in the TT that involves sexual content?
The game is based around mechs and the constant wars through humanity from as early as the 15th century all the way to 3300's. (barely)
Just because it wasn't ever mentioned, It doesn't mean it never happened... for instance no one ever said cars existed in Battle tech. You only ever see it in some few pictures and/or games however games are rarely if ever considered cannon. The reasoning behind me that cars existed is that in nearly everywhere, including the TT, there are roads and at times trafic lights so I doubt that they made a few lane wide road with specific dirrections for mechs that take up 100% of the lanes.
however back to the general 'furry'.
Clanners do 'cosplay' They base quite a few mechs on it. They attempt to mimic there totem animal. (mech looks, peformance, abilities, etc. good eg is clan ghost bear and the mech "kodiak" "grizzly" "bear cub" and that's just 1 clan out of the 25+. ) If anything the clanners seem more of a die hard furry then 80% of the current real life furries when seeing it in that light.