I have had a reply about the flag on the 2pj account:
Jagex was concerned about the security of the 2pj character as it appears to be a heavily contested account.
They took the action to disable the Jagex Account 2pj was linked to in order to secure 2pj until its true owner contacts them to claim it.
To prove ownership, you will need to supply proof that
you
created 2pj. Not that you created the Jagex Account but that you created the 2pj character.
If you have that proof please use the 'Contact Us' button on the
Unable to submit an account recovery
support page.
My comments:
The character will remain visible on the OSRS High Scores for the time being but, if unclaimed after three months, will eventually drop off.
Here are some notes about how to succeed at account recovery:
Account recovery
