The thirteenth characteristic is selective populism. However, seeing as de-platforming and counter protesting are both applications of this tenant, so if we are to say that Antifa is against Ur-Fascism then they'd have to be against these tactics.
Ur-Fascism is contradictory to itself. These contradictions lead to a confusing definition of fascism allowing for anyone to be opposed by Antifa as having fascistic tendencies/ideologies.