>>14045947"perfectly habitable" but "no life at all" complicates the answer.
Your spit would presumably contain a large number of bacteria, definitely enough to begin forming their own colonies, but bacteria don't just thrive on nothing.
The bacteria in your mouth are probably dependent on things present in your mouth and food in order to reproduce. The environment you're spitting them into is essentially sterile- not lethal to them outright, but likely without any source of nutrition or energy suitable for their metabolisms other than what you spit out with them, they're likely going to starve.
It's possible there could be the right organic molecules present, and the right bacteria to feed on them in your saliva, but that might be very unlikely.
So I guess the answer is still "maybe".
