They rushed past the armoury on the way to the Tier 2 objective? Somebody doesn't have to die for them to get those.

Personally, I think Invasion would be infinitely more entertaining if it were more similar to a Halo-spun version of Unreal Tournament's Warfare or Assault modes instead of a hack of Territories and CTF.

Also, when the Elites get the core, a base alarm should sound off until it's returned or end of the match.