to be fair, he doesn't say that " We have ALWAYS elected celebrities to the office of President..." He says that, "WHENEVER GIVEN THE CHANCE, Americans have always elected celebrities as President." Meaning that, when they were a choice on the menu, we chose the celebrity. But celebrities are not always on the menu. Carter, Bush, Clinton, Nixon, etc. come to mind without even thinking hard.
"Now, you might argue that electing generals makes more sense than electing TV stars. But Andrew Jackson was one of the worst Presidents in history, and Grant was pretty terrible, too. They didn’t win because they had relevant government experience. They won because they were famous." This paragraph only goes to reinforce the notion that celebrities (as he defines them) are a bad idea. He's discrediting his own argument here.
I think the argument that we've done it before is meaningless, especially when he points out how it hasn't worked out all that well.
Art has a double face, of expression and illusion.