Hi Blindwonder! Probably by now (7 year later) you figured out the answer to your question about another guy on top trying to arm-bar you. Maybe this answer or my humble attempt to answer your question (because I have only a year of bjj experience) is the answer to myself because I had exactly the same concern initially. The way how I see it since the guy is in your half guard he won’t be able to do any armbars that would require legs. If he tries to do any other arm bars anyway with only his head and arm, try not to let him lock your outstretched arm between his ear and his arm. And I don’t think it’s that difficult to do.

Hey guys, I have a question about this technique. One thing I notice is that as I go for the frame against the guys neck, sometimes they stay tight, block my elbow, turn their head and start trying an arm triangle from there. Is there a way to avoid that? If the answer is already in a video somewhere, can someone direct me to it? Thanks