No, Air Lock is not a strictly better choice from a mechanical standpoint. Some people may feel Air Lock would be overpowering/too centralizing on this Pokemon, and it is their right to have their opinion and vote as such. Better, here means better design, not more powerful. People may not want an OU viable Pokemon that can remove weather. Again, read my first post on the issue of "If you don't like the ability you don't have to use it." That is not a valid argument, as we are trying to make well designed Pokemon, and if somebody feels that a second ability lessens the Pokemon's design, they have every right to vote No Ability.
Regardless, this isn't just a poll of mechanics, but of flavor as well. Flavor is just as important as mechanics, if not more important, when making a well designed Pokemon, else we end up with a Ice/Dragon Doughnut Pokemon with Flame Body and Spell Tag as it's abilities with a stat distribution of 150/150/150/150/150/150, and learns every move in the game except lick. For flavor, again, many people have stated they don't feel Air Lock fits the flavor of this Pokemon. It is their opinion. Because it disagrees with yours does not make it invalid.
I'm not trying to invalidate your vote; don't try to invalidate mine. If you disagree with it, fine. But don't say all the No Ability votes are strictly inferior to the Air Lock votes. Every vote is equal.
As for the comment on the number of Pokemon that have 2 abilities, not only have you taken it out of the context that I used it in, but you added entirely new context about OU pokemon. I am talking about good Pokemon design regardless of tiers; my point was to illustrate many Pokemon are well designed with one ability, and having one ability fits those Pokemon. If having two abilities is strictly better design than having one, every Pokemon would be given two abilities. Hell, why stop there, 3 is better than 2, and 4 is better than 3, 5 is better... let's just give every Pokemon every ability. After all, if you don't like the abilities you don't have to use them. :P