I think what he means is the higher outside temperature will increse IAT's and therefor possible pre detonation if the plugs were gapped higher. From what i understand plugs with higher gap will generally make more power but are more pone to pre detonation when the boost is raised. This is just what i remember from my turbo honda days. Lower the gap and it has a lesser chance of detonation.

Id really like to learn more about the basics of how spark plug gap affects a boosted engine and why. Ive tried everything on my car from 25-39. Im currently at 35, but am not convinced this is necessarily optimal.