Ha! You're probably right.
Reminds me of when I was playing Highland pipes at a wedding reception, alternating with a folkish band playing Irish trad. Every tune they played was off late 1960s to early 1970s Chieftains albums, as if they had these as their only source, and set out to learn every set on every album. When I mentioned this to them, they didn't know what I was talking about, seeming only vaguely aware of the Chieftains.
In any case the basic Sindt design is similar to the Susato, which in turn is based on recorders. The innovation is making the head out of solid brass, and refining the tone and performance. Here's an original Susato, machined from PVC stock with a cedar block.
I used to have Sindts in D, C, B, Bb, and A and they are superb whistles. The Bb in particular was terrific. They have a dark sophisticated tone and butter-smooth voicing. However I found the 2nd octave to have a Generation-like slight flatness, and when I got a Killarney D with bang-on octaves I kept that, and my modified Generations in those several keys, selling off the Sindts.