Cohors C is in place just for this type of occasion - members who are unable to contribute for an extended period of time. I understand that the transition from contributing to Ordo frequently to not at all may be jarring, but the option of simply joining Cohors C is always available if you prefer to leave your options open. There is absolutely no obligation or responsibility in C Cohors - you're free to do as much or as little as you want, and when or if you're ready to return, you can simply transfer back to B.