LV GFCI and MV are not the same application of course.But the graph is:
UL felt it good enough to be taken seriously here using it as a foundation on which industrial GFCI protection is implemented.
The NESC does say that the primary and secondary neutral should be connected when you have a MGN system.But I am theorizing that in some cases it does more harm then good.
2.4kv can be brought into the structure.
There is nothing in the NESC which says this voltage must be cleared under 5 cycles.
I'd like my theory challenged and discussed because its something I'm genuinely curious about.