No response, sadly, but I'll leave the following for any future visitors of this thread: I went along with the protocol anyway, trying to complete the one chinup, and moving to 2-3 as slow and as controlled negatives as possible. Still did 20 sets. By workout 5, my other, healthy elbow would be aggravated more than the original injured one on sets ~4 and onwards, thus leading me quit the protocol. I can still, yet seldom feel some pain in the elbow in question, usually once or twice per workout when setting up during the squat (despite a fixed grip and arm position). Hopefully it will only get better with time.