I mean, I don’t know if you provided much direct evidence at all. As I understand it, the argument goes like this: in our pre-exilic biblical books, certain vocabulary words are not attested that are in Genesis 1-11, but these are then mentioned in our exilic and post-exilic works, and so Genesis 1-11 is an exilic/post-exilic work. By that very logic, if I find a handful of vocabulary words in the entirety of Genesis 12-50 that don’t appear in our few pre-exilic works, I could use this same argument to claim that Genesis 12-50, too, is exilic/post-exilic. I’m sure neither of us would be willing to accept this argument.
If you could demonstrate that some vocabulary in Genesis 1-11 didn’t exist before the exile, then that would be something else. However, an argument from silence can’t demonstrate that. This is why I say that your argument might give an indicator, but definitely not a proof or serious evidence for why we should date Genesis 1-11 to the exilic/post-exilic period. In my view, I date the Pentateuch to the pre-exilic period since I can find a large number of traditions in this work that originated in the pre-exilic period, some of them unknown in the exilic/post-exilic period. I’m not sure if I have any specific proof from Genesis 1-11, though.
Something that most of us will have to come to is that there’s no serious evidence, one way or another, to be able to date Genesis’ primeval history. We can make tentative estimations at best. I think this is something we’d be able to agree on.