Sun Tzu said something like "attack where you are strong and your enemy is weak". Mega-armor Man's strength is clearly in resisting physical damage. So trying to overpower that is probably a lost cause for your average security team. Trying to shoot him is like trying to argue with a Fixer or brute-force crash an AI (assuming they're both as efficient as armor guy). So OK, Mr. Troll is invulnerable to anything shy of high explosives or a Knight Errant team with miniguns and a Panther Canon. Don't try to shoot him!
Mr. Armor Man has to lug all that armor around and carry a gun, too. So his physical stats are probably pretty high. How's his Willpower? Any number of things target Willpower.
Don't have a combat mage and/or Adept with Commanding Voice? Knock him over. He's already encumbered. Put Mr. Armor on the ground and fire sticky stuff at him. Now the party can stay and free him or try to go on without him. Especially evil party members may just run away.
Don't have sticky stuff? How's his hand to hand combat? Aim for his gun then send in the Aikido master. All that armor is going to slow him down and the next thing you know, arm lock.
I especially like the last one because it has a real "cue dramatic music" feel to it. Arnold Schwarzenegger vs Steven Segal sort of thing. Any of the above work well if Knight Errant can come by for pickup. Once E-SWAT shows up, even Mr. Armor is going to lose. Since you probably don't want to hose Mr. Armor, just get some good dramatic tension out of it, the rest of the party can probably free him before KE shows up. The point is that the baddies may not be prepared but they're also not stupid. A smart security force will do better than a well equipped security force.
