the Infection and the artifacts (massive Spoilers)

[Peanuckle]

The entire science team got infected without much discussion about how, so my guess is that it's airborne, or maybe the virus directs itself with its hive mind. Philip gets infected with the virus from Red somehow, so it's probably airborne considering Red was in that furnace the whole time.

The artifacts are Tuurngaiit, and they segment a host's personality to make it easier for the virus to take over. Very devious.

Presumably, a year 2000 strike squad with all of Philip's briefing will be adequately prepared with sealed suits. And flamethrowers everywhere to burn the virus out of the air.

I would've preferred a choice as well, but I'd have made the same choice Philip made. Despite the Tuurngaiit posing as a benevolent entity that just wants to be left alone, you can't avoid the fact that it takes over the minds of innocent people and bends them to its will. It's also interfered several times in humanity's history, to it's own ends. Killing it is the morally correct option.