I wouldn't do it, I've powered up a L/H and Z/EQ to max, even though less than optimal defenders. (I never attack with Snorlax) It's worst case scenario moveset Snorlax, but it's Snorlax.
Everyone's situation is different, if you've got the candies and the dust, and the likelihood of getting another strong Snorlax anytime soon seems nil, why not? I'd of powered up that Snorlax a month ago, before I had a super lucky hatching stretch.
It's defensive DPS is horrible, a Chansey of the same level with Pound and Hyperbeam does more defensive damage per second? Can one of you mathematicians confirm this? Or tell me I'm missing something? Really didn't expect that?
It does have high CP though and will sit atop most gyms if you max it out...