Roxas wasn't thinking alcohol was the issue. That, as far as he knew, had a distinctive odor. He was thinking more along the lines of other things that could be put into punch that could cause problems. Magic or not, there were a lot of possibilities.

"Sora, you're... really acting kind of weird." He was trying to sound stern, but anyone actually paying attention would realize he also sounded worried. Boy, did he wish he'd caught Sora before he'd gotten into the punch.