OK, Correction you are doing something for systemd in the postinst script.
I still think this needs to be changed: - Remove START_DAEMON - Disable the initscript AND the systemd service on new installed by default - Then call update-rc.d minissdpd enable (or disable)update-rc.d is taking care of enabling both systemd and sysvinit scripts, this is the canonical way of doing this.
