At first I was thinking maybe he was one of the monsters Shii-san have to exterminate and this would turn out sad. Well It turned out sad but certainly not in the way I expected. Sorry I doubted you Baku-Baku
Should've suck just a tiny enough amount to have her survive. Youre a real human bean still bakubaku. I doubt he was just resting there at the end, thought maybe he could have some unique immunity system.
The conclusion is willfully somewhat ambiguous. Perhaps the author will leave things that way, or perhaps there will be a clarification — happy or sad — in a later episode.