It sounds to me like the model is ‘the candidate needs to have a (party-aligned) big blind spot in order to be acceptable to the extremists(/base)‘. (Which is what you’d expect, if those voters are bucketing ‘not-seeing A’ with ‘seeing B’.)
(Riffing off from that: I expect there’s also something like, Motive Ambiguity-style, ‘the candidate needs to have some, familiar/legible(?), big blind spot, in order to be acceptable/non-triggering to people who are used to the dialectical conflict’.)
Embarrassingly, that was a semi-unintended reaction — I would bet a small amount against that statement if someone gave me a resolution method, but am not motivated to figure one out, and realized this a second after making it — that I hadn’t figured out how to remove by the time you made that comment. Sorry.