The first sentence is clearly "headline English", judging by the grammar. Anyway, "Jerry Seinfeld says..." means "Jerry Seinfeld's opinion is that...", in this example. It doesn't mean he habitually opens his mouth to literally say it.
From a grammatical perspective, you could also understand the headline as presenting a fact (=use present simple).
You're right about the second sentence - it's a report of a specific event in the past, and Seinfeld's exact words.