It seems if you stay to the FAR right (no guarantees here) avoiding any helicopter at all you can climb over the smashed portion of wall.  Don't fight, just avoid debris.

The wiggle trick works, slowly but surely.  Then the bots, once you are free seem able to follow magically.

Oddly even turning on noclip on didn't fix it.  (of course I realized while typing it that if it was THAT easy it would have been the first post) but the wiggle works.  What is even odder is that while you can shoot your guns you can activate your own health kit.  I suggest a different "gate" for this arena.  Crash the copter elsewhere (ostensibly caused by the copter) while changing a wall to have a hole.  It isn't as elegant and it beats such an annoying and apparently common bug..  But, what do I know of these things. 

I have no idea what that means except that noclip, of course, lets one literally fly through the entire map.  You'd think it would free you of physics objects or ANY objects or perhaps it only works on walls and their game limits.