One meta belief I have, is that I think "on the face pursuing idealistic objective A, but actually being tilted toward selfish objective B" is better than "openly pursuing objective B".

Many seem to believe the opposite, typically saying something like "at least the latter is honest".

I feel like what this misses, is that maintaining the face of pursuing idealistic objective A, and using A to coordinate a large coalition, is a pretty big speed bump against attempts to pursue B too brazenly. When "the mask comes off", things actually become much worse, and strategies that pursue B at high costs to other values (including A, and also often general human decency) become unlocked.

Are there any good arguments against this intuition I have? (Whether generalized, or about specific situations)

I think you are spot on. 

In pursuing A above the internal pull toward B, one aims for a higher self, an improved version. 

When we choose this iterative model toward the best version of ourselves, we receive much more than if we had chosen B. 

It might take longer to achieve A, but the delay is worth the effort. Succumb to the lure of B, one also reaps an empty heart and a mind awash in resentment.