This behaviour is not affected by the force flag (the force flag deletes the host from I/O groups, even if it has any vdisk mappings in those I/O groups). For example, the force flag does not override the policing.
The same behaviour as rmhost, the policing will allow the I/O group if the host is already offline and at least one other host is mapped to the volume. It does not allow the io group to be removed if the host is the only host mapped to the volume and the volume is busy.