Stephen Colbert wasn’t so impressed as other TV talent that Florida Sen. Marco Rubio showed up for CNN’s town hall on school gun violence Wednesday night. “Just showing up isn’t that impressive; he works for those people,” Colbert said of the event, attended by about 7K people, including survivors and parents of victims of last week’s mass shooting at a high school in Parkland, Florida. Colbert said Rubio – aka “man who just received his cash from the NRA” – was the…