The story of the Thomas-Rasset suit --- a civil suit, not a 2B1.1(b) criminal sentence argument --- is basically about how those 7 figure sums don't hold up in actual court. And that suit was about material with clear commercial value, not 1942 editions of botany journals. I think this example supports my point, rather than challenging it.

A 6 figure sum did hold up in actual court though -- it initially landed there a few months before he died, and was finalized a few months after. So from the perspective of someone watching this at the time, it's still really not that ridiculous of a worry.