That casino may have been complying with their contract agreement with the manufacturer (WMS).
It's definitely a shame, but the companies that make slot machines often don't want the older ones ending up sold to a casino overseas (or anywhere for that matter), that could reduce orders for new machines. And they don't want to mess with selling them to private owners like us. Seems like they'd want to keep some of the parts for repairs on the same model machines that are still in service at other locations, but they have their reasons and it's most likely got to do with money.