I don’t use the Sorter and yet it often seems to launch at startup/login. The option to “start at login” in the sorter preferences is off. It’s in my account login items, but I just manually removed it (for the umpteenth time . My theory is the sorter gets re-added to login items after every update whether or not you have the preference to start it at login enabled.
I’m not sure if DTPO adds it back any more often than that.