Yeah, people shouldn't be using Antifa symbols unless they are literally prepared to fight Nazis. This isn't a game or a fashion statement. Being part of Antifa has always carried risk of physical harm, even during more relaxed times when people just derided them as being extreme teens.
The Antifa in my area is super serious I speak with them online. If I decide to join I wont be wearing any pins or anything that will blow my cover though.
They are 100% serious about it and are armed. They stood up to the white lives matter protesters back in December.
The movement is underground but bigger than people think and is gaining members all the time.