Yeah, I tend to consider any question of sexuality in TFs doubly moot because one: there has never been any indication that any more than 10% their population is female, which makes one feel that restricting them to only hetrosexual pairings is rather unfair, and two: there is enough continuities that show that they reproduce via a third party (the Allspark or Vector Sigma) as to make the issue of hetrosexuality pointless anyway.

But then I have a long history of reading slash and know most of the fanon on various reproduction methods - including the fact that plenty of ficcers will merrily write mech-preg with almost none of the issues that it's squishy counterpart, mpreg, gets.

TL;DR, yep, giant alien robots. The rules of us squishies need not apply.