Jim has been answering questions over on Twitter and this tidbit of information came up when a fan asked if he had any involvement with Guardians of Harmony. He replied saying that as far as he was aware it was just the name of a toy line.
While we have posted before that Hasbro has trademarked the series in regards to the production of "entertainment services, namely an on-going animated television series for children" it's possible all along that it was just done to cover all the trademark bases for the property. It's also possible they could still be thinking of a spin-off series or maybe took out the trademark in case they ever wanted to visit turning the line into a show down the line.
All we do know is that Jim isn't working on anything related to GoH and so far he is only aware of the brand as a toy line.
Thanks to Jess for sending it in!