Better, I'd say. It'll help seal any joint, and it'll also help prevent it coming undone, which PTFE won't. But the better option, I'd agree, is to have a suitably-sized tubeless valve in the first place, so you don't have to bother with extenders at all. Then you don't need PTFE or Loctite.
Or Loctite 542. Better option for valve extenders IMHO.