User blog comment:B214/Question and Answers 6/@comment-24.113.252.213-20160803051908/@comment-24.113.252.213-20160803061713

That's a very good reason.

But purely for the sake of arguement (I like to consider all possibilities), we know that Kuisha is very talented in using her Demonic Powers (both common, and her Clan's ability: Hole Magic), so she might have rigged the seals to unlock when Sairaorg wants them to, or he raises his Touki high enough.

In the Rias vs Sairaorg Rating Game in vol. 10, Sairaorg went up against Xenovia, Kiba, and Rossweisse. As he's "powering up", we see the seals on his arms and legs appear, then dissapear, signifying that they have been "unlocked."