Not knowing exactly what was said, it's hard to respond properly. But this is something that should not be taken lightly. Sure people don't agree, but any sort of discrimination is totally unacceptable.
Just remember that neither he nor his father, as he claims, is "bashing" you. They are bashing something that they feel is wrong based on a stereotype, and misconstrued beliefs that they have either formed, or been taught. (ie religion, school, politics) There is no need to leave the forum. If it's a problem, report it to Simon. Continue riding and continue to use this site as a resource. Ignorance is the greatest threat to this world, at least intelligent people "got your back".
This is a General Moped forum. Sexuality has no place here. We are here to create a community and talk about bikes. Lets all keep it that way.