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OOPS! After reviewing Owen's map, I realize I was confusing the Wando and the Soccastee formations. Owens gives a date of 200,000 ka for the Socastee. Your blue-line graph shows sea level at that date being lower than it is today, so the same conundrum still applies. (The Wando in that area of the Pee Dee is riverine).

There is a marine (littoral) facies of the Socastee formation that stretches to about 30 km inland from the present coastline that exhibits bays. The area I referenced earlier does not exhibit them. I think Owens interprets that area as a backswamp; I do not, for reasons I posted previously. But let us not lose sight of the original purpose of this discussion. Extrapolating from your sea-level graph, the Socastee must have been exposed subaerially somewhere between 200,000 and 180,000 years ago. That upper portion of the Socastee (in the Pee Dee region) does not exhibit bays, while immediately adjacent areas of the older Duplin formation do. If meteor or cometary impact at any time in the last 180,000 years had caused the bays, then bays should exist on the aforementioned area; but they do not.

Owens gives a date of 200,000 ka for the Socastee. Your blue-line graph shows sea level at that date being lower than it is today, so the same conundrum still applies.

Maybe not. I went back to have another look at the abstract(?) of the study I posted in #225. Ran across this little jewel I recall reading but dismissed(?) because I had found what I was looking for in the previous sentence. From that abstract:

It follows that the present elevation of the substage 5a shoreline cannot be explained by uplift or subsidence, and that relative sea-level positions for substage 5a along the South Carolina coast were approximately the same as MIS 5e or the present day.

You'll need to reread #225 to get the whole picture but essentially what this 2005 study concluded, amongst other things, is the 5a layer(ca. 82 ka.) and the 5e(ca. 130-116 ka.), were virtually the same. I don't quite know what to make of that given the "blue line" graph indicating otherwise, except that the blue line graph is possibly/likely wrong? IOW, your arguments are holding up, at least under this layman's scrutiny. Bravo........so far.