Same reason female tears generally attract support, and male tears - repulsion. (And yes, there are exceptions that decide nothing.) In other words: general automatic responses and reactions, partially constructed socially and partially biologically.
For example: there have been studies, that showed that both gay and straight women are more likely to be aroused by the opposite (for gay) and same (for straight) sex, versus gay men tend to ONLY be aroused by men, while straight men tend to only be aroused by women. To summarize: women are more likely to be bisexual (i.e., be aroused by both sexes). I don't remember where the study was published, but I could probably dig that up if you want me to. In any case: as a consequence of this, it would make sense that, biologically, a gay woman wouldn't repulse a man, since he, biologically, still feels he might be able to get some (and isn't 100% wrong, to be honest), while a gay man doesn't evoke that reaction in straight women.