Rusty wrote:

The original Multiple Mirror Telescope (built in Arizona in 1979) had
six surplus 72-inch mirrors that were supplied by the U.S. Air Force.
The six mirrors were replaced by a single 6.5 meter mirror in 2002.

Yes, that possibility occurred to me. The MMT blanks were, according
to the UL current at the time, left over from the KH-8 program. Maybe
that's what the current story is confused about.