Again, you're talking out of your butt.
How do you figure he owes us? He acted, he got paid. Tit for tat. Done. Beyond that, he doesn't have to do anything.
Now, if he were living in a gold beachhouse, being served drinks with umbrellas by trained monkeys, while tossing bales of money into a fire, screaming “Screw you all!”, then yeah, that'd be a jerk thing to do.
But he decided he didn't want to do the Hollywood thing anymore, and spends his days in New York hanging with his kids and writing music.
Here's the reality of the situation - he liked working on Ghostbusters, he didn't like working on Ghostbusters 2, and he talked with the game producers, but they couldn't come to an agreement. End of story.
Also, just so you know, Harrison Ford didn't make Indy 4 just for you.