I don't think they've been reluctant to use real force, I think they've been waiting until the public is 100% against these people and they've got a solid body of evidence.
The American government has arrested a ton of organizers on federal charges, but they haven't gone after the top people.
Imagine if they'd arrested a couple of hundred Antifa organizers and gave them charges that would lead to them being in jail for the rest of their lives, then sent the top-level to Camp X-Ray in May?
People would have been outraged.
If that was happening today though, no one would give a fuck.
As it is there's been hundreds of Antifa organizers sent to Federal prisons to await charges that will have them locked up until they're senior citizens and no one has given a fuck about that.
No one will give a fuck when their top-level is treated like terrorists in a month or two either.
They will use real force, but the US government's idea of real force is to lock you in a for-profit jail and use you as a slave for the rest of your life.
Antifa is already starting to find that out now, and they're going to get a serious taste of that in the future.