How about the legitimate customers who were afraid to use his business because of what their neighbours might think? It takes a lot less than "Oh, is that the ISIS guy?" to kill a business in small town America. And what about the customers who tried to get through, but due to the hundreds of crank calls, couldn't get through and switched to another plumber, thereby losing current and future business?
Most small non-internet businesses are basically out of business without usable phones, and if this business is anything like my plumber, his number is stickered to every single piece of major work his company has done since 1984, and changing his number would undo all of that marketing effort. I'm certain I'm not the only one that calls the company that did the installation when I need service, at least if I'm happy with the original work -- Even if it's not a warranty issue, I know they deal with all of the brands of equipment installed, and they aren't going to claim the original installation was defective and charge me an arm and a leg fixing made-up issues with the original installation either.
$1M isn't much actual damages for current and future business, and some punitive damages would seem to be in order if the dealership failed to remove the logo as contracted, if that was part of the arrangement (which, admittedly, will likely be difficult to prove)