This seems like an overly elaborate explanation. If you have polling data that shows you are 10 points behind, you change your positions to close the gap. There's no sense in sticking to principal and losing.
And I have issues with this idea, that we can know the populations well enough, to slice and dice and shave population groups until we have a 51% winning vote. That doesn't seem real.
True. There's no telling if any of the promises or language will translate into action once governing. In normal times, breaking campaign promises would carry consequences for reelection of the candidate (or the candidate's party), but it's anyone's guess if that applies now.
Candidates stake out an initial position (or affiliation) and then court voters at the margins of that initial position, often by modifying that initial position (edit: or by modifying their messaging around that initial position).