We always come back to the same reasoning that kept blacks out of the general military -- prejudice.
This is a straw man argument. You are claiming that for me and many others here to consider homosexual behavior unacceptable in the military (or as being unhealthy) is nothing but the same kind of prejudice that used to be legally enforced on black people in the US. This is a false, abhorrant argument that many black people and people of other ethnic or racial minorities find extremely offensive.
Homosexual acts are a chosen, voluntary set of behaviors, which can be learned, chosen, or renounced. Being a member of a particular race is immutable, unchosen, and values neutral. Go take your "prejudice" argument over to a black church and see what they say! See if conservative black people like being compared to men who like to have anal sex with each other.