I think it just comes down to business.
If you are a tech company saying "we are happy to employ gay people" makes you sound all progressive and fair. However there is no business risk that you are taking on here because nobody is saying that gay programmers write worse code or anything like that.
Now contrast that with the US military and the shitstorm around allowing openly gay people to serve. Since there are many conservative types in the military who threatened to resign if openly gay people were allowed to serve you have the argument "allowing gays to openly serve will hurt our national security".
Now even the most liberal gay friendly person might see that as a valid argument.
Now contrast that with the US military and the shitstorm around allowing openly gay people to serve. Since there are many conservative types in the military who threatened to resign if openly gay people were allowed to serve you have the argument "allowing gays to openly serve will hurt our national security". Now even the most liberal gay friendly person might see that as a valid argument.