Given those constraints, I would probably write something like "Money would pay for marginal output in the form of increased collaboration on the technical analysis necessary to determine as well as possible the feasibility and difficulty of FAI" for my first sentence and elaborate as strictly necessary. That seems rather more cumbersome than I'd like, but it's also a lot of information to try and convey in one sentence!

Alternatively, I would consider something along the lines of "Money would pay for the technical analysis necessary to determine as well as possible the feasibility and difficulty of FAI, but not directly-- since the best Friendliness-cognizant x-rationalists would likely already be working on similar things, the money would go towards setting up better communication, coordination, and collaboration for that group."

That said, I am unaware of any reputation Eliezer has in the field of interpreting people, and personally haven't received the impression that he's consistently unusually bad or uncharitable at it. Then again, I have something of a reputation-- at least in person-- for being too charitable, so perhaps I'm being too light on Eliezer (or you?) here.