I assume you would also agree that the loss you posit is “not by any means a sure thing.” It will surely depend on her performance in the job, unless you believe that her appointment in and of itself is a serious blow to the WFP. I don’t see much support for that.
If you fear immediate negative effect because McCain is a non-entity, I think you can relax. She is far from a non-entity under any normal meaning of the term. She is well known around the world, has experience in relief work, and will have good access to Biden (who wants her on his side in 2022 and 2024).
Anyway, I’m all for weighing gain and loss. We just see the scale differently. Time will tell.