Apart from the fact that he was bringing up her "gayness," though, is the sheer effrontery of saying of someone he doesn't seem to know personally "If you asked Dick Cheney's daughter . . . she would tell you . . . ." IMO, if you were crude enough to ask, she would probably (and rightly) tell you to mind your own business.
Look, I live in NYC. I have a lot of gay friends, business associates, etc. If I presumed to speak for any of them - say while out having a drink, much less in a public forum, they'd drag me over the coals without mercy. Likewise, it is considered the height of bad taste to ask someone if they're gay. It really is a personal matter.
The fact that some gay people are applauding Kerry has nothing to do with their personal feelings on the subject and everything to do with their partisan feelings about politics.