Good article. It seems the 1969 test disallowed speech that "is directed to inciting or producing imminent lawless action and is likely to incite or produce such action".

Encouraging people to violate mask orders would fit this definition.

Perhaps, if the speaker incited a crowd to remove their masks at a protest in a municipality in which not wearing a mask was illegal.

Simply advocating that people violate mask orders doesn't pass the imminence test.