Pike's report won't be useless despite the fact that neither Starfleet nor the UFP have jurisdiction on Majalis.
The next Starfleet officer who meets Alora when she's in danger won't be eager to help her now that she's been exposed for her management of child sacrifices (assuming that Starfleet ever goes anywhere near Majalis again, which is unlikely).
The Federation may well extend an offer to Prospect VII to join if they agree to not attack Majalis anymore. Therefore, Majalans who can't bear the First Servant thing anymore will know they can have a decent life on a colony helped by the UFP.
