My charitable interpretation is that it was political winds, but possibly not in the way you're implying.

I do believe that Obama was 100% cool with gay marriage, but believed it was politically foolhardy to admit that publicly and in policy positions, but was able to advocate for his true feelings once the political climate changed. Still not awesome, but understandable from an electoral perspective.

I'm not really sure about Clinton. I would guess he's personally in favor of gay marriage and gays in the military today, but hard to say what his views might have been in the 90s (as I was a teenager at the time who wasn't all that interested in politics).

Also on supposedly-liberal people doing homophobic things: let's also not forget that California voters banned gay marriage statewide in 2008. 2008! And this was a ballot measure where all voters got a say, not something passed by the legislature.