By "can't reason with" the vile Trump hater, Ruben, who wrote this means that you can't lie to and expect them to believe your lies. It is a massive source of frustration to the Trump hating socialism loving media that Trump's base looks at their endless spewing of lies and hatred (when they look at all) and ignores it. The media feels entitled to tell people what to think and when that doesn't happen they don't know what to do. Lies are the only weapon they have.
They act likes demons being subjected to an exorcism.