I know this about OHKO moves; the problem is that with enough evasion and defense boosts Glalie gets a ton of opportunities for Sheer Cold to hit (especially if the subs don't break). The role of Sheer Cold on Glalie isn't to be accurate but to allow it to get past threats that can't be KO'd by a boosted Ice attack. Furthermore the flipside is that if accuracy is lowered by Moody, Glalie can still spam Sheer Cold. Certainly Glalie might be unreliable and probably doesn't merit much use on its own but the real question here is whether with proper team support (Yawn, Memento, Swaggerplay, etc) it is threatening enough to merit a ranking, and it seems to me that it is. The best way to answer this question, however, would be to ask someone who has used Moody Glalie. Aegislash is actually one of the best checks because of its access to Sacred Sword, unless it gets unlucky with Sheer Cold, but the fact that there is a great check to it doesn't necessarily make Glalie unviable.