@falsifian@www.falsifian.org TLS won’t help you if you change your domain name. How will people know if it’s really you? Maybe that’s not the biggest problem for something with such low stakes as twtxt, but it’s a reasonable concern that could be solved using signatures from an unchanging cryptographic key.
This idea is the basis of Nostr. Notes can be posted to many relays and every note is signed with your private key. It doesn’t matter where you get the note from, your client can verify its authenticity. That way, relays don’t need to be trusted.