This APPEARS to work, since the SailPoint source is showing as Disabled in the UI.
BUT, it doesn’t really update the source. I get the same number of identities when I run the query, and after a refresh, the SailPoint source goes back to Enabled for he user.
I think this may have been caused by another issue with our tenant, whicjh caused some actions to be inconsistent. That has been corrected, and now the API call works to successfully disable the account.
When I did the disable through the API, and through the UI, the accounts stayed disabled after a Refresh.