How do I defeat the guy in the armor in Stuck on Crushing?

Evade him for awhile and fight some of the other men who jump down eventually. Most of them are easy one shot kills with any gun just to occupy your time. Keep running from the big man until a goon with a grenade launcher shows up just above the red door. Kill him and the grenade launcher will fall to the ground intentionally for you. Use it on the big man, 3 or 4 shots will kill him. If you loose the launcher, (as I did) then just kill gooneys until you have four grenades. Keep chucking grenades until he has no armor, then use a kal 7 to finish him off.

The easiest way is by where he jumps down there should be a big yellow crate. Jump on and go all the way to the right. Doing that makes it easier to hit him and gives you cover he can't flank.