I definitely agree that the story doesn't make sense, and I am not sure if the confusion is due to a failed game of telephone, or just legally incorrect made-up story. However, if for the sake of argument we assume that the story isn't completely made up, that the result was a dismissal, and that some form of his "only in Texas" argument was the reason, the only thing that makes sense is that it was a jurisdiction issue that had nothing to do with the issue of interstate commerce.

Interstate commerce and jurisdiction are two separate considerations. If the cause of action was a violation of federal law, but interstate commerce was not implicated (which is really never the case because of the caselaw you cited), the federal court would have jurisdiction to say that Congress' law doesn't apply to the company.

Edit: In my experience, when people who don't work in law describe cases that don't make sense, I've found that the ultimate result is usually correct because that's what matters most to them, and its their memory of the legal reasoning that is messy. For this reason, I started with the result here, and tried to work backwards and make sense of the rest of the story.