I think this puts the RFL in a slightly tricky position, assuming somebody has something more concrete than that video as evidence.
I'm not really a massive fan of treating match footage like CCTV, and I wonder how the complainant found it.
But, the bottom line is that it isn't language he should be using at all, and certainly not in public. The cameras are not hidden, so if he said it I couldn't bring myself to have much sympathy.
It is quite likely that he never even thought about any connotations, and it's a word that's crept into common vernacular in some circles (I used to play in a football team where it was bandied around a lot, and we had two gay players). But that used to be true of casual racism as well, and we wouldn't expect the RFL to turn a blind eye to that.
I suspect that there's some mileage to be had out of some education work here, and that might be more useful than a ban. Fine to be given to Stonewall or similar, some very public challenge to casual use of the word - which I bet a good half of SL players have in their insult bank.
All assuming there's some more substance to this than the Youtube video.
I am also assuming that the ref was content that it wasn't aimed in his direction, otherwise I would hope that the other F word being alleged would have been enough to get a red card.