I am thinking about changing the check in the CUPS Snap to /usr/sbin/cupsd, as cupsd.conf is a configuration file which does not go away by a simple uninstall of CUPS (dpkg -r or apt remove). Also a user perhaps wants to keep the file for migrating back. cupsd definitely goes away when uninstalling CUPS and can esily be put back by installing CUPS again.
So I will change the CUPS Snap appropriately …