The rights are not absolute — yelling ‘Fire!’ in a crowded theater, child porn, etc.
I like that Cruz is standing up to her but he probably won’t win the argument based on this line of reasoning.
Running the argument out with every possible counter argument would have shown where the argument is vulnerable. Doing this before making the argument will reveal whether the argument will stand or fall. If you realise it will fall - make a different argument.
Take Sandy Hook for instance, it would have been just as easy to kill as many kids with a car by running a group of them over, or by hijack a bus and ram it into a above ground fuel tank. That could happen just as often as mass murders with “assault rifles”. This argument illustrates the real problem as not being assault rifles, it's deranged individuals.