Vampirism Runes 6th set bonus is a Stun Breaker

Title says it all. This is listed nowhere in game or in the Wiki.

I discovered this last night because I was testing out the Vampirism Runes in the PvP lobby because I read on the Wiki that the 6th set bonus doesn't activate until the player is below 20% health despite that the Runes say 25%. Not only did I confirm (and report) the bug, I noticed that in the Combat log that the leech effect for 690 health also listed it as a Stun Breaker when I hovered over it. I then confirmed it by letting the Warrior npc in the PvP lobby CC me at low health.

Just thought I would throw that out there for people to discuss because I hear it has been a hot topic whether or not Vampirism or Scholar runes are preferable in WvW or sPvP for Thieves.