It wasn't "we have to go in, better arm up." They could have watched the house and gathered more information. Since they have a warrant, are cops allowed to thermally image a house to get a headcount? Technical question: would that work or am I imagining something from TV?
Nah we don't have thermal imaging that precise yet, also, the thermal difference between outside the house and inside the house sort of washes away any lingering body heat you might be looking for in most cases.
