There are different kinds of casual settings. In my social circle, if you criticized someone for calling a magazine a clip, you would be instantly made fun of for being such a pedantic nuisance. A clearly left-leaning media outlet like this is likely targeting an audience more like my social circle than ones who would be pedantic about silencer/suppressor or clip/magazine.
A lack of precision is only really a problem when it would cause confusion. In the context of the article, nobody is confused about what they mean by "silencer". A good example of this is that, even while complaining about calling them "silencers" rather than suppressors, the top comment still didn't have any confusion about what was being discussed.