That is not correct. The US Government and the Philippine Government could not agree on the new lease amount so agreed the Americans would close the base and leave. Most personnel had already left when Pinatubo blew up. Those that remained helped to clean up the mess before departing.
Yes, the Philippine government wanted too much money, but I think Pinatubo was part of it. It also, would have taken a ton of money to clean it up. I was at Clark in 87. Fortunately, they were able to get all the aircraft out of of there, before it went off.