Thordarson's position came under pressure following following the team's recent slump in form, which has seen the Reds win just one of their last 13 matches.
Chairman Peter Ridsdale decided to wield the axe to give the Reds a chance of reaching the play-offs.
Ridsdale didn't employ Gudjon and speculation about his future increased as the Reds slipped down the table.
Personally, I think Gudjon has been harshly treated and the fans expectations have been unreasonable considering the position the club was in only a few months ago.