If Dreier had been my Representative, I would have gladly voted for him too. When I lived in the San Gabriel Valley, I was not in his district (I was then stuck with Marty Martinez). But the homosexuality issue was certainly a factor for some voters.
My Congressman, Jim Kolbe, was "outed" by a radical gay group in '96 when he voted for DOMA. It never hurt him politically, so I don't understand how it would matter in an area like LA.
BTW, if someone chooses to keep his sex life private, I think it's abhorrent for anyone to bring it to public attention.