Khmer Supposed to Need TCs for Vills?

Ok, so like, I get why you need a TC to make babies, right? You need somewhere to garrison privately for a few minutes. And of course, towers always have an archer on duty, and the inside of a ram gets way too stuffy, and Castles always leave the front door wide open, etc.

But then last night I was playing Khmer and I needed to build a TC so I could wall hop some vills, and it was cheaper to rebuild TC than go up to Feudal for towers (375 vs. 500 resources), so I had to delete my TC (you're only allowed to have one TC in the Dark age, unless you convert a second one). So I thought, no worries, I have 4 houses, each one has 5 garrison slots, TCs have 15 slots, so that's 3x, TC villagers take 25 seconds, so that's 3x25 seconds = 75 seconds, so I'll be able to pump out 4 villagers every 75 seconds, which will average out to 1 vill every 19 seconds.

But when I clicked on a house (ANY of them) there weren't any options. Even when I garrisoned a mix of males and female villagers. Am I missing something here or is this just an oversight?