It's very much like saying that, which doesn't mean it's not persuasive reasoning. It may not be ultimately rational reasoning, but it appeals to many people. That's why it's called the sunk cost fallacy. :)
Yep, I was referring to the fallacy. I know people don't always make rational decisions—and there are many other considerations here besides—but I thought it worth pointing out that it's not quite so obvious that the large companies would be against patent dissolution.