Of course, that assumes that they consider non-Vulcans to be part of "the many." Now that I think about it, there's no particular reason to believe that's a commonly held Vulcan value/belief.

It's Spock's belief... but Spock was half-human, and the other Vulcans mostly seemed to think he was perhaps a bit too attached to that side of his ancestry. I think that they definitely assigned a good deal less weight to non-Vulcans. (Not zero weight... they did help out Humanity a bit on first contact, after all... just less weight).

Besides, given that the Vulcan High Council is pretty influential in the Federation, they can steer things their way at least some of the time; they might not be able to persuade the Federation to follow the path of maximal utility, but they can signpost the path (and warn about any cliffs in the area); the other races might not listen to them all the time, but they're quite likely to listen at least some of the time, severely limiting the utility loss.