Has somebody possibly not explained the scope of the Project to him?
The plan is to use the knowledge out of Keltham's world to revolutionize all nonmagical farming, medicine, clothmaking, mining, metallurgy, manufacture, roadmaking, all of which actually scales up much higher than Golarion has taken it so far. Probably also use the methodologies out of Keltham's world to revolutionize a bunch of magical stuff too.
Roughly, the plan is to turn Golarion into its own version of Civilization, as the people of Golarion may want to become that, and the Project is step one of it.
If all dreams fail and the Project ends up being worthless - as does not particularly seem likely at this point to be the case - then the alchemist still gets to keep his usual and customary fees, and the people on the project can sign non-disclosure about whatever secrets of his he revealed to them along the way. Alternatively, if the Project plays out to the extent of being able to capture one gold piece of value created for everyone in Golarion, it ends up worth something like a billion gold pieces, on that theory, and 0.1% is worth a million gold pieces.
This is what the god-war a couple of weeks ago was about, FYI; it started with Zon-Kuthon trying for a decapitation strike on the Project two days after Keltham arrived in Golarion.