Did Commodore cheat with the quad density floppies?

Hi there,

I was looking at floppy disk recording schemes and I am wondering if the 
8050/8250/1001 floppy disk format with over 500kB per side was actually out 
of spec of even the Quad Density disks?

The recording frequency was increased from 250kHz to 375kHz (× 1.5, for the 
innermost i.e. most critical track/speed zone). That resulted in a much 
increased number of bits per inch. See here:
https://extrapages.de/archives/20190102-Floppy-notes.html

What do you think?

Thanks
André