From the article, it doesn't seem that unusual: Dr. Cicoria didn't suddenly become an artist, it still took him a bit to get there. Specifically, the "no previous training" from the title simply doesn't apply.

The sudden part was gaining interest and passion in music - and it can be linked to him being struck by lightning.

As for the musical process - hearing music in his head, desire to listen and play, hearing his own music when starting to play other pieces - that's not at all unique. I can't vouch for everyone, but as a musicmaker, I can say that this is how a lot of people make music.

I think it's not that much unlike the flow state in coding, where one wakes up with the problem already loaded in mind, has ideas about structures and algorithms in the shower, and then figures out how to code it all during the day. Writing down the notes is - literally - coding music.

I think that if you can get a song stuck in your head, you also have this potential to hear new music in your head, and thus to make it. It just can get easily drown in all the other noise that life generates. Some people just need a shake to turn the other noise down.