There was that time Delta generated an "H8GAYS" PNR. [1] Pretty sure that's valid Crockford encoding too :) however, to your point, it does rely on 'A'. "H8G4YS" would likely still offend someone out there, though, given the kerfuffle in [1].
> But as White points out, it’s a bit surprising that Delta didn’t block this particular combination as a possibility. “I’m sure they removed many four-letter words that would be seen as offensive,” he tells the Post. “I’m surprised that ‘gays’ and ‘H8’ weren’t blocked as well.”
Oh sweet summer child (meaning Jeff White, not OP/GP). As someone who has implemented a censorship/filtering list, this is a UX problem on the same level of decideability as the halting problem. You can spend boundless time curating a list to flag/grawlix every possible string that would offend even the most prudish of prudes, and some would still get through. Such as the superficially benign "EATTHE"
[1] https://newsfeed.time.com/2013/12/17/delta-airlines-is-very-...