Today I used mc cap on a dwarf warrior in AB and they followed me through the portal but didn't get zoned out. Then someone else used their mc cap on the same warrior and did the exact same thing, ran through the portal and they didn't zone out.
I'm guessing this particular player was somehow bugged, or now that enough Alliance has cried (because you didn't do shit when I made a ticket about it a few months ago, telling me it was perfectly legal to mc people out of bgs and encouraged me to do the same) you finally stopped this from happening.
Which is a real shame because pretty much the only fun thing about facing ranker premades is giving one of their shitters a deserter debuff.