I don't particularly want to defend homophobic chanting, but I'm not sure that you're making a useful distinction.
The mocking of Sol Campbell's nervous debilitation - to the tune of Lord of The Dance, if you recall - wouldn't unduly have distressed any Spurs fans who suffered from mental illness. They'd have known that Sol was being targeted for being Sol.
Not that chanting is at its best when it is aimed at genuine weak spots. The reason that I enjoy the paedophile chant at Wenger is that it's so manifestly unfounded an accusation. Purity of malice is untainted by any coarse fact.