He has a great point. It takes resources to build up an audience anywhere, and then the assumption is generally that once you have that audience you've gained the right to speak to it. Facebook expects you to pay to build your audience (via ads) and then again to speak to it (via "reach"). This makes it a pretty bad idea to spend resources on building an audience there.
Will Twitter do something like this? I don't think so. But it's also a crapshoot whether your tweet will actually be seen or too far down your tweet stream for someone to actually see it. I still believe that email marketing is The. Best. place to build an audience because you have permission to send a message to someone that is almost guaranteed to at least have its headline read.
Of course the rules of the road apply wherever you build an audience, meaning you can't spam or abuse the privilege to talk to them. But all things being equal, owning the channel has some HUGE advantages.
The power of owning the channel is a huge advantage, I wish more people understood. Email marketing used to be the best, but email read rates are usually less than 20% and it's over a few days. There is a better medium to build an audience that guarantees they get read...And definitely agree about not spamming or abusing the privilege.