That early episode is essentially the origin of "a show about nothing." When describing their idea for "Jerry" to the NBC execs, George uses that incident as an example. Summarizing: One of the episodes will just be four of them waiting for a table at a restaurant. Why would people watch that? Because it's on TV! Not yet...
It's very meta because of course when you say it out loud it does sound horribly boring just like the NBC guy says. But the Seinfeld audience is aware that the Seinfeld characters (now the ones writing a sitcom about their personal experiences) actually experienced this situation, and to the Seinfeld audience, it was actually a very funny episode, therefore realizing that the Jerry audience would also find it funny.
It's very meta because of course when you say it out loud it does sound horribly boring just like the NBC guy says. But the Seinfeld audience is aware that the Seinfeld characters (now the ones writing a sitcom about their personal experiences) actually experienced this situation, and to the Seinfeld audience, it was actually a very funny episode, therefore realizing that the Jerry audience would also find it funny.