This should have gone like, "Hey, in a few months we're rolling this out and wanted to give you a heads up so you know before anyone else, since you're a major API user. We wanted to offer you a grace period and special pricing. When's a good time to chat we'll fly out.". Fly the sales team over to where he lives, wine and dine him, etc. This is what sales people do all day long for deals that are like $250k+. For deals that are $20 million a year you'll have all parts of the company bending over backwards trying to win that.
This is all just my opinion based on what I've read so far.