You really can't consider the boosted sp. defense base stat, as it is removable by any other weather ect, it isn't always there like a base stat. Just saying, not making any agrument at Kyurem at all.
I'd say that's fairly true now, with Ninetales and especially Politoed in the mix, but Bologo's point still stands because 4th Gen Tyranitar basically did have an unchallenged Sp.D boost (really, abamasnow? don't make me laugh). We dealt with Tyranitar alright last gen, and Kyuuremu this one will be not so different.
But then, both Tyranitar and Kyuuremu have terribly questionably typing-- particularly from the defensive side. They also lack the speed to avoid their common weaknesses. If TTar and Kyuuremu had their base stats allocated more effectively to avoid hits, I'd have second opinions about both.