For what it's worth, the 0.5 changelog (not 0.51--check the OP for 0.5 info) says the lack of male characters is a known issue at the moment.
This developer always handled updates like this, releasing a new version with more features and customization but each subsequent update would only have one or two characters, and characters from previous versions were often removed. This is nothing new. The big assortment of characters we had in the 0.4 versions were mostly from modders adding them all back in.
Even though it's disappointing, it makes some sense if you think about it: he was probably focused entirely on female bodies and making sure all of the clothing options and new mechanics/features were functional. Maybe he understood how long it's been since the last update, how his fans have been getting impatient, and maybe he thought "I can either release what I have now, or take another few months to work on the male characters. I'll release now and add in male characters when they're ready"
Of course I am entirely speculating, I could be completely wrong. But the fact that he listed it as a "known issue" tells us that he plans to bring back male characters.
Anyways, give it a few days and I'll bet some of the modders in this thread will have male models jury-rigged back in. Probably some of the old characters, too.
Glad to see this game's back!