Your source for this?
I hardly can imagine they never got the idea to use normal sensitometers and simply put a pinhole before it.
My source at Eastman Kodak - who definitely would know!
Apparently there is no known practical way to modify the normal sensitometers in a way that will allow them to both produce and measure those low light levels in a way that is sufficiently accurate to produce repeatable and consistent results.
And there is no business case for spending the $ necessary to research, design and build such a sensitometer themselves.