In Vino Veritas
As an astute commenter pointed out earlier, his blood alcohol level was .12—too high to be driving, for sure, but just about the right level to bring out the wit at a cocktail party. Certainly Gibson, an admitted alcoholic, wasn't plastered with a .12 blood alcohol level. In fact, if I'm not mistaken, that's only .02 above the legal limit in some states.
No, .12 is enough to loosen the tongue, but it's far from enough to sever it's connection to the brain and it doesn't free anyone from responsibility for what gets said when that tongue gets to flapping.
So, to sum up: Mel Gibson is on record making anti-Semitic comments, he's the author and director of a well-known anti-Semitic film, and he refuses to disown or even mildly disagree with the views of his father, a prominent anti-Semite and Holocaust denier. What's to debate?
As Andrew Sullivan writes, "What we just found out for sure was always hiding in plain sight." Or, to put it another way, Mel's confirmed the true 'passion' that dwells in his heart, and it's far from 'brave'. (You can insert your own Lethal Weapon one-liner here.)