Well... he could use the trick used a few time in Season 2 of the TV Show. Basicly, laying a corpse or killed Walker over yourself and laying completely still. The Walkers will ignore you then.
This is more plausible in the alley situation as the, still warm, body of Ben would distract them as he is the easy food. Kenny could kill the one attacking him and hide under him.
In the building, not so much.
I noticed one thing about the building situation though: Even when you don't have extra bullets for him, so he should only have 1 left, you hear two gunshots as he struggles with them. This may hint so him actually being saved by someone unknown. And seeing they immediately move on when he is out of sight it is possible he just didn't have a chance to catch up again.
But yeah.. Stage 1 of grief for most
I'm in Stage 3 at this time, does it show?