The enterprise as walled garden approach to security seems quite out of date and is harmful to all parties involved. Like it or not, the Internet at large has made our life one big WAN party, and we need to come to terms with that sooner rather than later.
So how would that new approach look? The de-facto solution today is that security is more and more delegated to device vendors and cloud providers. But that seems worse to me than delegating it to the admins of your organization that you know and trust.
We need machines and global policy to help do this work and we need to stop putting faith in magic black boxes which we know will be thoroughly compromised (e.g.: all enterprise vendor equipment).
More on point, TLS 1.3 seems like a step in the right direction of thought: that you can improve your local security posture by improving the global posture.
He is right, it will be expensive. And he has a right to complain. Should the working group ignore him? It's a tough call. You risk forking standards when you start to do that.