Antifa is not an organization. It's an ideology. There are groups that call themselves anti-fascists, which have different views and methods, and there is no HQ they answer to. Just like MAGA.

Another example: banning zionism/antizionism or banning racism.

It can't work like that.

The focus has to be on criminal acts committed by individuals, regardless of their ideological affiliation.

Banning an ideology would be a direct and fundamental attack on the 1st amendment of the constitution.

It would lead to "guilt by association." A concept the Supreme Court has found to be unconstitutional. (NAACP v. Alabama (1958), Scales v. United States (1961), Noto v. United States (1961), United States v. Robel (1967), etc.)