I, personally, wouldn't have a problem with it.
But it doesn't mean that another poster wouldn't. What you said may have been levelled at one poster who was aware of it, but they were very generic things to say to a gay or bisexual male. Someone could have come to the forum, seen that, been offended and left. Even if it didn't have that sort of reaction, it could still be contrived as offensive.
The fact that you said it was a joke a day later, whether or not it was a joke, doesn't stop the reaction people had in the first place.