I'm not convinced that this is necessarily true. They advertised running Linux VMs during their presentation, they made a tool specifically for installing Windows on Macs and they even recently stated how Windows on ARM Macs is really up to Microsoft. If you could run Windows on an M1 Mac, it'd really turn it into a powerful and power-efficient "do-it-all" machine, since you could still boot into Windows and run that niche Windows software that you need from time to time.