The Edinburgh Gunners lock was dismissed during the defeat by Wales last Sunday for lashing out at Ian Gough.
Murray will now miss the Calcutta Cup clash with England next weekend while Nathan Hines has made himself available after retiring from the international arena a year ago.
But Nicol maintains the ban does not fit the crime where Murray is concerned.
He told The Herald: "Murray is not a dirty player.
"In fact, he is probably one of the least dirty players I have ever played with.
"His actions were instinctive, impetuous and, probably, reckless but they were not premeditated.
"Murray has been banned for three weeks by the disciplinary panel, which means he will miss the England game.
"Does this 'time' equate to the crime? I don't think it does and I believe the sending off should have been deemed punishment enough."