Well, if you were promissed a certain amount then they should certainly pay you. But the whole "interests" thing is utter bullshit ...
That is the "normal" thing to do when you're owed money. Ask any lawyer or financial "expert".
And when he saw no money he decided to wait till he was replaced.
I don't know. Maybe he trusted Axl to pay him one day ("don't worry, you're in my band, you're my mate, we wrote songs together"...) until he found out the truth.
Pure speculation of course, maybe one day we'll hear what supposedly happened.