He doesn't like that woman to be a cold corpse. He prefers her to be warm, unlike those specimens!
He did all of this just to save one person, and he didn't want to save the world, but no one ask for his opinion, not even her, before they began shoving all the responsibility on his shoulders. He was suffocated with it, and often he would have urges to leave the base, but when he thought there was a possibility she would accept him when he developed the medicine, he persevered, but now...
To hell with it all, he doesn't care a single bit about this world. He only cares about one thing. If the formula perishes with him, then so be it.