Yeah, it's plausible. A lot of people are saying "he couldn't survive" or "If they make him survive it would be too far-fetched", but remember, in this show the zombies aren't actually trying to "kill" people--they are only trying to "eat" people.
The point here is that they don't really care who is alive as long as they have a fresh pile of guts in front of them. So, when that fool landed on Glen, it is feasible that he could've had time to shimmy under the dumpster before they started eating him.
Of course, if he laid there for too long he would be a goner, but they really only showed a few seconds of "someone" being eaten. We have seen plenty of episodes where the zombies don't immediately devour every inch of someone's body. So, him being able to role under the dumpster is not out of keeping with the show, especially if most of his body was covered by that other idiot.