I'd like "serious scholar" defined. One can be a "serious scholar" and still be wrong! Are you saying that there were no scholars in the West post-600 bc who didn't accept that "the sphericality of the earth was well established"? I find that incredibly hard to believe, and if there were serious scholars who thought otherwise, then Krauss's point stands.

The question is simple: did all or most mapmakers, post 600bc, realise that the earth was spherical? If they did, your intervention is justified. If they didn't, it isn't.

Yes, they did. I can't say that there weren't a few cranks out there who argued that the earth was flat (there almost certainly were, as there definitely are today) but the vast, vast majority of writings that come down to us from c.600BC onward and touch on the subject show no doubt at all as to the earth being a sphere. The orbits of the sun, moon and celestial firmament and the fact that things disappear over the horizon if you go far enough are the usual evidence cited when the point needed to be demonstrated. By "serious scholars" I mean anyone taken at all seriously by their peers and posterity. Certainly anyone whose works were considered worth copying out and disseminating.