How about if the "snow" is actually somewhere in between rain and snow, and turns into aqua as soon as it hits the wing because OAT is +2 and the wing might be even warmer from having been in the hangar all night. Don't fall for the commercial pressure, but surely captain's discretion would be appropriate in such a scenario rather than blindly listen to what some ass-covering de-icing crew is trying to tell you?
Same discretion that's being used when HOT table says 20-40 min and after 23 min you have to decide whether to accept take-off clearance or not.