It's not. I guarantee you they know the difference. They are choosing to use common vernacular to speak to their audience.
People know what a "silencer" is because that's what it's called in movies and TV. Much fewer people know that it's actually called a "suppressor".
Meet the audience where they are.
I'm not going to take their word that they are illegal firearms when they demonstrate ignorance of firearms and firearms ads.
Not all details matter for the broader discussion. Being a gun nerd has very little to do with understanding their impact on society.
The impact on society and whether you arent ignorant about firearms is irrelevant. They claim the firearm ads are illegal but dont seem credible because they use outsider language and incorrectly imply firearm ads are illegal in general.