Given the grind has already been specified as an espresso-level of fineness (we're talking about a cold brew recipe), most of the grinds are going to be able to

Given the grind has already been specified as an espresso-level of fineness (we're talking about a cold brew recipe), most of the grinds are going to be able to get through the metal filter. The original suggestion of plunging slowly and gently is entirely sensible, since it's the only variable available in the context.