It reads like the usual thing you see with retro gaming types: someone, who probably has all the right in the world to do so, makes their version of something without the original person’s name on it, and original dude has a little fit about how they’re being denied their due credit or whatever.

Like, not the first time this has happened, and certainly won’t be the last time it happens.

Though I doubt he really has the ability to change license on a whim like that, but it also doesn’t matter, because it’s not like that’s retroactive. Just fork it before guy had a fit, and forget he exists, and move on.