That is such a terrible comic. "Free speech" is a broader cultural concept than "legal first amendment rights", and conflating them like that is at best ignorant but more likely a deliberate tactic for those in favor of censorship.
So does the freedom of speech include you being able to invade my home to scream at me? Or force me to go to a church? Or listen to you while I'm walking by? Seriously, I'd love to see this form of extreme speech survive a day in any big metropolitan area. It's likely its adherents would wind up with broken jaws in less time than that.
Are you seriously comparing expressing ones opinions in a more or less PUBLIC space to assaulting someone on his private property? Or enslaving you so you got to church? Are these the mighty arguments madmen such as I need to refute?
No one is preventing anyone from expressing their opinion. Just expect people to call you an ahole for expressing it. Or in other words: deal with reality and stop pretending you're exempt from criticism (noticed that I was free to post my opinion on here and you were free to criticize it without getting hurt, right? My feelings and body are intact and I hope yours are too.).