"Homosexuality is another threat the West just like immigration."
No, it isn't. There were homosexuals in ancient Greece, probably just as many as there are today. There will be about the same number (proportionally) 50, 100, 200+ years from now.
There is no growing threat from homosexuality. They don't pass on their genes. They come from heterosexual parents!
Moreover, culture and upbringing has virtually nothing to do with whether a person will turn out homosexual. It's almost entirely genetic (that's why you can often identify gay/lesbian people just from their physical appearance). Anyone who is a race realist should be a realist with regard to sexuality, too.