Dwayne,
The script you are looking at is used after a migration from UPM to PCP. UPM did not have a concept of self-care but it was added when PCP 9.0 was developed. So if you migrate from UPM to PCP, Prime self-care will be off for all users. The script is a bulk enable if you want to give all users self-care access. You can also use it to bulk turn off Prime self-care for all users. It is not used to control the Prime Self-Care check box.
Prime Self-care for a user is selected by a check box when the user is first added or can be changed by bringing up the Manage user UI (the little "i" next to the userID in the subscriber record.
You should also check that the CreateSelfCareAccounts rule is set to True.
There may be a couple other things to check but that rule would be the place to start.
Regards