Comment by schoen

I've thought that the "attempts to destroy" and "attempts to overthrow" are limited in the sense of "imminent lawless action" and not "mere teaching or advocacy". E.g. if someone says "we should have a dictatorship of the proletariat/guardianship of the Islamic Jurist/integralist monarchy/national socialism/etc. instead of the social order that we have now", that statement doesn't cause or create those systems. Tolerating it presumably does increase the chance that one of those systems will eventually come to power (because advocating it could be an important step in creating it), but there's no guarantee of that, any more than there's a guarantee that tolerating any other idea or belief will lead to that idea or belief's ascendancy or general acceptance!

(And on the other hand, not tolerating these ideas also opens the door to making other beliefs shared with any of these belief systems taboo.)