>> McKay probably saw this as a bit of a holiday, while the Nigerians saw it as work.
That's probably his way of unwinding and managing his psychology after a match. It's a bit misleading for the article to bring it up as a disadvantage since he's obviously a strong player who has probably competed for some time, so he should be expected to know what works for him.
Also, you can perfectly well go to the pub without coming back with your pants on your head. I usually drink half a glass of wine, then go home and code. No reason why the guy didn't have a light drink then got back to his hotel and trained.
By contrast, the Nigerian's practice of playing 48-hour games and studying non-stop during their flight sounds more performance-degrading to me (having played a board game competitively, I won't say which). But, again: what works for them works for them.