Hi @soda,
Please see the replies to your own post Questions about compute omega. As you see, LAMMPS still computes \omega following the standard rigid body procedure.
When I originally wrote this post, I wanted a method to compute the “molecular” \omega because I needed a LAMMPS fix to remove rotation from a molecule during a simulation without altering its vibrations. I already had my own Fortran code that computed these quantities but to implement a fix I needed LAMMPS to compute it as well.
I was successful but due to the low interest in the original proposal I decided it was not the effort to polish and submit the feature (it was a niche usage).