The only surprising aspect of the Halliday incident was that Willie Collum gave the free-kick, but not for the reasons advocated on this thread, such as it being soft or otherwise unworthy of punishment, rather because Willie has a habit of not seeing things correctly when Rangers are involved.
In this case, Willie got it right.
The Livvie player had his hands on Andy's back, and when this happens anywhere in the defensive third the defender always gets a free-kick.
More often than not it occurs near the corner flag as defenders try to shield the ball and attacking players put their hands on the defender's back, down he goes often too easily, but nonetheless it is quickly followed by the whistle for a foul to be awarded against the attacker.
I am not defending Andy's dithering nor am I making a claim that such incidents are not indeed soft awards, but they are consistently given, had it not been so yesterday then it would have been an injustice against Rangers.
Simples.