I think you are giving this guy way too much credit if you actually believe his free speech bullshit. I'm not buying it. Why is he preaching free speech but intends to charge for DM's?
Twitter is not like Linkedin so DMs should be free and we have control to restrict who DM us in the setting which is enough. Linkedin is all about business. So profiles of Top brass are locked if you upgrade your plan to restrict job seekers from bombing your DM.
By the way, is he talking about "free speech" or "free manslaughter"? Because in Elon's world the tag "free" comes with eye-rolling if you have been following his account on Twitter.