informing SIAI that you will fund them if and only if they require their staff to exhibit a high degree of vigilance about the possibility of poisoning the existential risk meme by making claims that people find uncredible

I believe you are completely ignoring the status-demolishing effects of hypocrisy and insincerity.

When I first started watching Blogging Heads discussions featuring Eliezer I would often have moments where I held my breath thinking "Oh god, he can't address that directly without sounding nuts, here comes the abhorrent back-peddling and waffling". Instead he met it head on with complete honesty and did so in a way I've never seen other people able to pull off - without sounding nuts at all. In fact, sounding very reasonable. I've since updated enough that I no longer wince and hold my breath, I smile and await the triumph.

If, as most people (and nearly all politicians) do, he would have waffled and presented an argument that he doesn't honestly hold, but that is more publicly acceptable, I'd feel disappointed and a bit sickened and I'd tune out the rest of what he has to say.

Hypocrisy is transparent. People (including neurotypical people) very easily see when others are making claims they don't personally believe, and they universally despise such actions. Politicians and lawyers are among the most hated groups in modern societies, in large part because of this hypocrisy. They are only tolerated because they are seen as a necessary evil.

Right now, People Working To Reduce Existential Risk are not seen as necessary. So it's highly unlikely that hypocrisy among them would be tolerated. They would repel anyone currently inclined to help, and their hypocrisy wouldn't draw in any new support. The answer isn't to try to deceive others about your true beliefs, it is to help make those beliefs more credible among the incredulous.

I feel that anyone advocating for public hypocrisy among the SIAI staff is working to disintegrate the organization (even if unintentionally).