Okay I'm fixing this in lextwt, yarnd and twtxt.app (takes a different path). Soon you'll be able to write shit™ like (<this>) and it'll get escaped and rendered correctly on the page. Basically you are really writing HTML here, but not intending to do so, Twtxt never supported HTML, and I don't think it ever should. We extended the format to support basic Markdown, and I think that's where it should end.

Probably time we wrote a Spec for this really.