You fired your top talent. I hope you’re happy.
Tony Robinson

While Rick’s response is expected, it seems shortsighted and immature. He should have seen this as an opportunity — after all there are years of hidden/undocumented functionalities that are likely to baloon the re-write by 2x or more. Rick should have been professional and smiling his way to the door — these types of situations can easily be converted into nice “SME” consultancies when an under-thought re-write project goes horribly overbudget because of oversimplified views of what the system was doing.