You're not the only one who's said it's not, and I'm not the only one who's said it clearly is.
> Clause 3 of Parity runs directly contrary to OSD 9.
There is nothing clear about OSD 9, or at least nothing to do with the reach of copyleft:
https://writing.kemitchell.com/2018/11/05/OSD-Copyleft-Regul...