<p>Frank Grillo, who&#8217;s been a mainstay in the DC Universe with his role as Rick Flag Sr. in &#8220;Superman,&#8221; &#8220;Peacemaker,&#8221; &#8220;Creature Commandos&#8221; and next summer&#8217;s &#8220;Man of Tomorrow,&#8221; posted a video message supporting ousted DC Studios chiefs James Gu</p>