The Invisible Crackhead route is probably your best answer against someone implementing that form of stalling tactic. Because your instructor isn't doing much to regain his posture, take the extra time to set up a High Double Bagger, which in turn would make it easier to transition to Invisible Crackhead. From there you can have an easier time Zombie-ing to Invisible Collar, or you can actually Super Pump to lock that near shoulder. However, your success may vary depending on your flexibility, leg strength/length, and the relative size of the person in your closed guard.
A simpler method to getting an easier Zombie is via elevation. While controlling your partner using Mission Control, use your free foot to push on the hip in order to lift your butt off of the ground. Sneak your Zombie arm under the forearm or wrist and punch up as you drop your butt back onto the floor. The logic is that you forcibly create space to Zombie and your opponent can't match your descent.