I hate to break it to you, but judging by the outcome of last year's election, this statement is provably false.
This means his opponents' ideas are by-and-large rejected by civil society, and the amazing irony is, he invited those ideas to be tested out in the open. Kirk gave a platform to ideas he and his audience abhor.
If someone's views are "too egregious" to be tested openly, it's almost always the case that the person suggesting this knows their own views wouldn't hold up. It's a tell that they know they've lost the argument, before it even happened. Calls for censorship and deplatforming are the key tell for how feeble a person is.
If their ideals are so great, why can't they survive under scrutiny?
Only part of Trump's voters thought this would be the outcome, but we're stuck with the results.
Please, quit playing word games. We've moved past that, and America won't survive if you treat this like your high-school debate club.
At that point, you're not having a useful debate, you're platforming them and lending their ideas legitimacy.
For neo-nazis, appearing on the debate stage is itself a win, and a chance to spread their ideas to the crowd, even if they "lose" the debate.
The Paradox of Tolerance requires neo-nazis be told to go back under the rock they crawled out from, not given platforms.