It wasn't the Progressive Conservatives... PC stood for Progressive Canadians. They were made up of those in the Progressive Conservatives who fought the merger and didn't want to join the newly amalgamated Conservative Party.
They lost the right to use the name Progressive Conservative so they named their new party Progressive Canadians so they would still have the PC short form... it was sure to cause a bit of confusion... but that was kind of the point I'm sure.
Here is a
LINK to Globe Story on the topic