I didn't find the exchange particularly extraordinary. The judge is expressing his opinion that he doesn't buy what Shapiro is selling. The judge will have already studied Shapiro's written arguments before the trial. During the oral arguments, the judge has a chance to clarify things from the written arguments. I haven't read the full transcript, but I imagine Leon didn't feel fully convinced by the written arguments, asked Shapiro to address some of his concerns, continued to feel unsatisfied and decided to move on. That's how it goes sometimes. Time is not unlimited and there are always too many things to cover.
At the very least, Shapiro's argument is complicated and novel (it has never been used as a part of an anti-trust case before). Tellingly, the Bloomberg article doesn't not even attempt to explain or summarize the economic theory. It's not like Leon is pigheadedly refusing to accept some widely accepted, basic economic principle.
If we are going to criticize the ruling, let's do so by discussing the substance of the judge's opinion, not courtroom banter.
Oral argument is usually just for clarifications/questions over the written briefs. Judge Leon likely later read the written briefs on his own time (that is his job, after all).
