So with macOS Monterey (present beta, 21A5543b) it seems that the libRSBypass.dylib that is the core of the patch is not working, causes the Rocksmith2014 app to crash. Revert to the unpatched application with Steam and it is able to launch. The issue is reproducible, and I am not the only person to encounter this (I'm on a 2020 Macbook Air M1, but another user on a M1 MBP is having the same issue here -
So it looks like the libRSBypass.dylib may need to be addressed for Monterey.