Yep, they're fairly misleading. The threat level is the "quality" of NPC you'll encounter, but the "quantity" remains up in the air. For example, I've gone on threat 1 missions where I've ended up massively outnumbered in a pitched battle with NPCs coming in on dropships seemingly forever. I've also gone on threat 5 missions where absolutely nothing happened and it was a walk in the park.The problem with that, though, is that the "threat levels" for foot missions are basically useless for accurately describing potential danger.