That is not really a valid way to put it. Rather, there is claims made in their theory of origins, and they are positing additional facts not attested to in Scripture, to see if that could render these claims consistent with the evidence. That is a valid reason to adjust a model.
Of course, even with that adjustment, because of the global flood no amount of adjusting is going to make the genetic data fit their model. They are going to have to give that part of the story up, it seems to me, or posit ongoing miracles (which even YECs do not want to do).
I was just giving you a view of a YECs reasoning for rejecting a global Eve.
A thoughtful reason is that they are willing to let evidence reshape the narrative on non-essential details.
Presuming they were homozygote clones would be inconsistent with the data. Moreover, if Adam was a mosaic, with different DNA in each his cells, Eve would be too. So this a theory that preserves what they think is important in the passage, and might be less inconsistent with the data.
This is a thoughtful reason for rejecting a clonal Eve.