if we want more IQ 150+ people to get involved in existential risk reduction, then perhaps SIAI needs to make a greater point of seeming non-weird long enough for smart outsiders to switch from "save time by evaluating surface weirdness" mode to "take seriously and evaluate arguments directly" mode.

What about less-smart people? I mean, self-motivated idealistic genius nerds are certainly necessary for the core functions of programming an FAI, but any sufficiently large organization also needs a certain number of people who mostly just file paperwork, follow orders, answer the phone, etc. and things tend to work out more efficiently when those people are primarily motivated by the organization's actual goals rather than it's willingness to pay.