It's odd that the 'General Partner and Co-Founder of Craft Ventures. Previously: Founder/CEO of Yammer. Original COO of PayPal.' came to such a mistaken belief regarding fighting words in modern legal practice.
Carelessness in fact checking seems to becoming more common even among otherwise competent people.
Repeating something I said downthread: being a General Counsel for a VC firm or a company has very little to do with Constitutional Law or First Amendment law or, really, even defamation (which is something that does come up in companies). If the GC of a typical company has to deal with a defamation suit, they retain outside counsel to do it, because the law is hyperspecialized.
First Amendment Twitter runs a cottage industry of dunks on well-regarded lawyers saying stupid things about 1A jurisprudence. I'm not a lawyer, but I follow 1A Twitter, and I think this would qualify; for instance: the "incitement" section refers to "clear and present danger", which is the Schenck standard, which was famously overturned by Brandenburg. My understanding is that this, to 1A law, is about as fundamental as knowing the difference between a hash table and a tree is to a software developer.
Carelessness in fact checking seems to becoming more common even among otherwise competent people.