B- is fine for Klefki right now. For a defensive/support Pokemon, it hardly checks anything, and with neither Taunt nor any offensive presence of its own, it invites a free switch to other defensive Pokemon that'll completely ignore it and set up their own game. I'd imagine that outside of the confusion shenanigans, most teams would want a Deoxys-S in its place, doing much of the same thing with less predictability. As a matter of fact, I still don't know what the correct response is when I see Deoxys-S in the preview.
Also, just to clear the air, Swagger + Foul Play is neither a new nor revolutionary strategy, and I doubt it holds much clout, if any, in Klefki's ranking.