[throwaway316943]

To me it seems he’s clearly saying that if they decide to use force then we should be prepared to respond in kind not that we should use force to suppress irrational argument. The end of the first sentence maps to the end of the second.

[didibus]

How I interpret it is not that we should use force to suppress irrational argument, but that if we are failing to counter intolerance with rationale argument in the public opinion, than we should be prepared to do even more to counter it, maybe even to use force. And then he lists examples of what he'd consider cases where more than just countering with rationale argument would be justified, and those are: denounce all arguments, not willing to discuss at a rationale level, not willing to listen, believing they are being deceived, using pistols and fists.