Let me explain why. Then I am never going to discuss Looms again, because, honestly, I think they're a terrible idea. I generally try to avoid all discussion of them, but this one fan won't let me do that.
Even if you accept Marc Platt's invention of Looms in two out-of-print novels published during the wilderness years,* despite it contradicting a lot of TV canon, it makes absolutely no sense to assume that any other planet in the universe had looms.
Looms were an impartial solution to the fact that the Pythia cursed the followers of Rassilon to be barren and infertile, as part of a Gallifreyan political struggle. She literally caused Gallifreyan mothers all over the planet to have miscarriages. I know some people advocate Looms as proof of Time Lord asexuality, but the book that mentions them has Time Lords having sex and bearing children in wombs before and after the curse is lifted. More importantly, I'm really uncomfortable with the idea that asexuality = infertility, let alone that it's a punishment and a curse.
The Pythia cursed Rassilon's followers due to a power struggle between her and Rassilon for rule of Gallifrey. There's no way her curse could apply to Traken or any other random planet, since nobody else had anything to do with that dispute.
It's bizarre to bring Traken into alignment with Gallifreyan history. The Fourth Doctor had never gone to Traken before — he said so. Nyssa has little experience with the Time Lords. Gallifrey is off in its own little pocket behind its transduction barriers and has few dealings with the outside universe.
Also? It is very strongly implied that Nyssa has sex in Circular Time. That's part of her "Nyssa's growing from girl into independent young woman" arc in "Autumn," in which she has a love affair that includes kissing, heavy petting in the woods, and going to bed with the bloke. The audio doesn't cover the R-rated bit, because it's not porn, but he wakes up in bed afterwards and calls out for Nyssa to find she's slipped out of bed and left him a memento to remember her by.
*At the time Lungbarrow was released, the BBC had washed its hands of the show and let Virgin do whatever it liked with the books. What it liked was to hire die-hard fans as writers: (Gary Russell: "That great thing where at the time you think, ‘Wow, this is real foresight, this is good thinking by Virgin. They want to find exciting new writers.’ With hindsight of course, you go, ‘It’s because they’re bloody cheap, and they couldn’t afford big posh writers to keep doing Doctor Who books because they had to do them on a shoestring.’") I've heard Marc Platt himself doesn't subscribe to the Loom theory any longer, although I have searched and searched and can't find the quote where that came out.