Note: rare to this specific place, and even then "never in 12 years" could be just as much due to them not getting out in the first few days of clear ice before there is some snow.
Possible, but also possible that a bunch of us live here, hike every week, are familiar with the conditions and know that the deep freeze is almost always preceded by snow that keeps this from happening.
A couple of years ago I had the opportunity to walk on ice that was similar in a different region. It was fascinating to be able to see down through the water, and I realized at some point how unusual it was to have that many days below freezing, that it could be safely walked on, without any snow to cover the lake.