If someone says, "Hey, this hypothesis doesn't fit the data very well because it doesn't fit me and I'm part of the data," amending the hypothesis is not to appeal to that group but to create a better hypothesis.

If you survey libertarians, they score low on all of the original five (https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1665934, Figure 1). This leaves two possibilities: (1) they have deficient moral intuitions overall, or (2) they prioritize a different moral intuition than those five. When you listen to libertarians, they sure sound like they're making moral arguments, so it's worth investigating the possibility that the theory is incomplete.

And it turns out that libertarians do score very high--higher than anyone else--on liberty-focused questions (see various other figures, especially Figure 6).

The main piece that's missing is really strong evidence that this clearly documented psychological distinction is actually a moral difference and not just the consequence of a moral deficit.

Anyway, that this is to "appeal to libertarians" as opposed to "doing science" seems unfounded.