He has an account on the site. The level of activity is not relevant in terms of allowing Grumpywriter to post Jordinio's work, however.
The procedures are not onerous to adopt a story. Jordinio needs to advise us in writing that he's placing the story for adoption and allowing Grumpywriter to proceed with it. Jordinio can place any limitations on the adoption, such as not allowing it to be readopted. Grumpywriter then will be able to post the story. We're not asking for DNA or notarized statements. We just need something in writing to deflect any future accusations of plagiarism should someone come across the story under Grumpywriter's account and decide to file a report. Feel free to take a look at the Adopt a story thread. We've had a few adoptions already, and it appeared to be painless for all involved.