They seem to be trying to increase the prestige of x-risk reduction.

What does that mean, specifically? As thomblake points out, some of the things they've associated with themselves are simultaneously ridiculous and useless, not prestigious. (They might appeal to fuzzy feelings of some people associated with futurism, in the manner of curing rare diseases in (fictional) kittens, and this way draw some funding their way.)

some people I respect are on some of their "boards," though I'm also unsure what to conclude from that

This seems to be the main source of power for this organisation: they invite people to their "boards", which has no apparent cost to neither those people nor the organization, and association with those people then draws both donations and further people for the "boards".