I used the modifier "perhaps", which was followed by acknowledgment that we don't know his beliefs (because he won't talk about them except in person.)
Brendan is (or was at the time of donation) ignorant, there's no sense in disputing that. I'm just tired of people labelling him as anti-gay, bigot, homophobe, etc.
Just a heads-up, this is a strawman developed by anti-same-sex-marriage proponents to provide a possible (though not plausible) reason other than denying people their rights why someone might oppose same-sex marriage (and you also have to buy that someone who wanted to grant same-sex couples those legal right would vote/donate/campaign/etc to deny them).
If you're going to assert it, you need to have specific evidence that the individual in question actually believes that.