Another idea, it sounds like he would like to play a few Tarantellas which would keep his right hand busy he could try and compose his own.
I'd start him with some actual repertoire if it were me. There are numerous things you can use, such as Bach's Anna Magdalena Notebook and Burgmuller's 100 studies.
.I happen to be an arranger there, I would know
If you want video game music, look no further than ninsheetmusic.org. It's the largest online archive of VGM music on the internet worldwide, with several thousand sheets on there.I happen to be an arranger there, I would know
if he is a gamer get arrangements of gamer music man they go after that stuff like gangbusters--there are simplified versions. This on below is immensely popular with students, too. It may be tough at first but if he's motivated he will work it out.you can also have him surf around and find something he wants to learn... teach him to improvise or read a leadsheet.it's tough when you are a new teacher... you are not bound by faber and faber...or Alfred, or Bastien... the idea is to keep them coming to their lessons... that takes precedence over what he plays. If you are working in a studio they will track your drop rate... if it's too high... you are done. Play music games, teach him theory, find out what he wants to play... you are not forming concert pianists.. take it one day at a time.
his mom is... A little high maintenance
Do you have any Tarantella suggestions that would be around his level? He's around Level 3 as per Jane MaGrath's Pianist Guide. I thought about Burgmuller, but that might be a little too difficult.