I'm not sure if it'd exactly be worth banning it. Well, maybe it would (nobody used's it by-hand as of yet, so it's hard to say), but I personally wouldn't like it, honestly. Altaria is sort of an underrated Pokémon, and with this mega-form, it's finally getting some chance to shine; seeing this taken away as instantly like this is, in my opinion, definitely not okay.
So far, those judgement are made from immunity, resistances, and weakness; stats and ability haven't been released yet, though (have they?), so I suppose a final decision can't be reached until they officially are.