Here's another possibility. We don't know that those "two beers" were 12oz. cans. They make 16oz. cans.
What if those "two beers" were 40oz. Mickeys Malt Liquor.
He could have been up til midnight and sick as a dog.
At 5:30, he might have had no alcohol in his system, but if he was hungover, that might be a reason to climb on the wrong aircraft.
My point is that we don't know the size of the "TWO BEERS", we don't know when those beers were consumed, we don't know who consumed them as he may have bought them for Clay and himself.
If he did comsume them, he violated Comair's policy, and wasn't responsible and didn't show much concern for his passengers.
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