The OP is suggesting that he wants to use his vote to encourage a Republican to do the right thing on a very narrow issue. The parent is effectively saying this focuses on a single tree instead of the entire forest. In a two-party system you are effectively voting for the entire platform and not for a single issue, so I have no idea why you consider his critique absolutist.
No, the implication was that you should maximize your agreement with one of the platforms available (two here). One issue voting most likely doesn't do that.
You then treated "reprehensible" as meaning the same thing as "not perfectly aligned".
Your followup treated "reprehensible" as meaning the same thing as "don't agree with everything".
We might agree on some things, but we clearly do not agree about what jacquesm was saying, because I think the original comment was fine.
I understand that some people will choose to minimize negatives while some will choose to advocate for positives when stepping up to the poll. We all agree on this idea and this has nothing to do with whether one person diesagrees with or isn't fully aligned with a platform. (This is where I'm losing your argument which seems to be harping on this idea.)
My meta commentary is that viewing the other side's policies (_some_) as reprehensible distracts from the politics and pushes people towards the minimizing negatives game because it inflates the impact of negatives because of the association of blame that comes with a term like reprehensible. "If you are republican and vote for their reprehensible platform then you are to blame." Now it's not just about disagreement, it's about social justice. And for that reason I prefer, of late, when people focus on advocating for positive change rather than voting against negative change. That is where the semantics do come in.
A response to this point would involve asserting that their policies are indeed reprehensible and we should treat the entire platform in such a way.
Strawman.
I'm not sure what other conclusion someone is supposed to draw. That's how the stereotype you used works. I'm not republican, I don't care. But I do know republicans and I know that calling the platform reprehensible isn't helping anything or changing any minds.
I can excuse it if you were only intending to present an academic example supporting your general point about single issue voting in a two party system. I often do the same and have fallen into the same trap before. But if that was your intention it was lost one me. Maybe work on slightly more finessed phasing to avoid the downvotes in the future?
IMO absolutist stances like this miss the entire point of politics which is to strike compromise in the face of disperate ideologies. Sure the two party system is broken, but the way to make progress is to focus on relevant issues one at a time instead of the entire platform.