The paradox of tolerance: Unlimited tolerance must lead to the disappearance of tolerance. If we extend unlimited tolerance even to those who are intolerant, if we are not prepared to defend a tolerant society against the onslaught of the intolerant, then the tolerant will be destroyed, and tolerance with them.
The Paradox of Tolerance disappears if you look at tolerance, not as a moral standard, but as a social contract.
If someone does not abide by the contract, then they are not covered by it.
In other words: The intolerant are not abiding by the terms of the social contract of mutual tolerance. Since they have broken the terms of the contract, they are no longer covered by the contract, and their intolerance should NOT be tolerated.