So. This made me curious so I sat down and listened to it.
First thing is first: I didn't think Powerman 5000 until someone actually talked about it. So I sat and played both. Short of the riff, there's maybe a feel of a homage to the song, and that the song has taken some liberties by using somewhat the same structure of the song, but wow, there's no infringement here. They don't sound alike at all.
You want a song that could have caused you problems if you're S-E? Mog. That's incredibly close to Tim Burton's "This is Hallowe'en" from A Nightmare Before Christmas. Anyone who says that it's a change of the FF5 music is basing it off of one 10 second part of that song and saying "SEE! 8 BIT = THIS SONG! NOT COPYRIGHT!"
...put both together. At the same time. And you will hear the songs be incredibly and eerily similar. THAT is a far better candidate for copyright infringement.
This is, in my view, a complete non issue. There's enough difference that it wouldn't trigger. And I used to listen to Powerman 5000 back in the day. When hearing Sephirot, I never even once thought of Powerman 5000. Mog? I literally yelled out "THIS IS HALLOWE'EN, THIS IS HALLOWE'EN!" when doing the boss the first time.
On that note, I'm indifferent to this song. I preferred Ravana.











