I'm only a little familiar with Seinfeld. My point about lying was first made (as far as we know) by Augustin of Hippo in the 4th century, and unless I miss my guess, Seinfeld isn't that old. Augustin's account has become the standard account of the criteria of lying.
You're missing my point. I imagine you were quite surprised that Trump became the Republican candidate, and then that he was elected President. I know I was. I know I'm also appalled at his conduct, and my impression now is that my worst fears about him are true. Fighting someone like this requires precision.
If you keep calling Trump a liar, you do nothing to help your cause. Trump is losing support of swing voters, but it's early in his presidency, and he can make that support back up (by, for example, goading North Korea into starting a war). His supporters believe he's much more honest than most politicians precisely because he tells you exactly what he thinks, and he won the Presidency arguably on exactly that trait. So if you want Trump to be a one term President, and you agitate for the same, you have to get his dynamic right.
