Is the F-slur unacceptable/inappropriate to use at anytime?

[T'Chenka]

I'm not opposed to the short-form version being used in certain contexts where it's VERY clear that it's meant as a parody / satire of homophobes and not to be taken literally.

The long-form version should only be used be LGBTQ people, but preferably not at all. Hopefully gay people eventually stop using it and hopefully black people eventually stop using the N word, at some point in the distant future.

[T'Chenka]

It's certainly acceptable/appropriate to use when writing literature -- books, plays, movies -- in order to convey the idea that some people are still homophobic.

This applies to literally any word in the english language.