The argument for people who are anti-genocide to vote Harris, is that Trump will not only be much worse than the current administration, but will not be able to be swayed by public pressure in the same way Harris might be.

It's also the "current administration". I'd imagine that despite all of the people pretending otherwise (and kind of buying the "She's Biden", weak-ass attack line from the Trump camp), a Harris-Walz administration will not be exactly the same as the current Biden-Harris one.

The vice presidency is largely a ceremonial role, and she has to walk a fine line while campaigning for the job of POTUS to not criticize the "current administration" that she's nominally part of and therefore is not likely to break with it very much publicly, but I would find it utterly unsurprising if she charted a completely distinct course from Biden on many issues when she assumes the role.