When is discrimination not discrimination?

If you weren't fortunate enough to miss pisshead McCain this weekend talking to Snuffalufagus, I mean Stephanopoulos, then you completely missed his I'm against discrimination except when I'm for it spiel.

MCCAIN: I just want to point out again, I believe that gay
marriage should not be legal, OK, but I don't believe that we should
discriminate against any American, because that's not the nature of
America, OK?

So what do you call it when one part of the population is not allowed to do something another part of the population can do because to allow that section of the population equal access would break some long standing tradition?

Let's see:

When certain people (blacks, women) weren't allowed to vote while white men were- we called that discrimination

When certain people weren't allowed into colleges (blacks, women) while white men were - we called that discrimination

When certain people (blacks, women) can't get a particular job or home or line of credit that they qualify for because they are not white men- we call that discrimination.

So how is it again that when certain people want to marry but aren't allowed to because they aren't what we normally expect to see in a married couple (i/e a man and a woman) it's not discrimination?

Seriously, anytime someone can show me a logical argument for why 2 people can't pledge to be responsible for each other in life because they are of the same sex- I will gladly stop calling it discrimination. But we all know there is never a logical explanation of discrimination, just selfish justifications for perpetuating it (like "I'm trying to run for preznit and I must appeal to the base by being a giant bigot.")

I know there are quite a few of you middling democrats out there who liked McCain in 2000 and maybe even in 2004- but he has shown his not-so-maverick side since 2000 and it ain't' pretty. Unless, of course, you think watching one more person take it up the ass from Georgie Boy while smiling with a mouth full of shit sandwich is a maverick move. Then there's been a whole lot of maverick made lately (uhm Lieberman I am talking to you too).