I see no reason to disagree with you on that, but my impression is that a lot of Burns scholars do, and have their reasons (which may not mean diddly to you or me). I find it hard, though, to credit the notion that "Burns scholars" in general would be ignorant of significant collections of Burns MS in publicly accessible libraries in the British Isles. They've had a couple hundred years to notice them, after all, and lots of theses to write.

Liland