Murray has been a mainstay of the Scottish side for five years but was surprisingly dropped from McGeechan's 22 to face the Welsh at Murrayfield on March 8.
Hines, who was dropped from the squad for last weekend's game against France, joined James McLaren and Robert Russell who were both promoted to the senior team after good displays in the Scotland A team.
Hines said: "It was a big shock for me that Scott was left out. I've spoken to him and obviously it's devastating to get dropped whether it's for your country, your club or even when playing as a youngster.
"But from a personal point of view, regardless of whether we're talking about Scott or not, it's healthy for players to be called in or dropped due to form.
"It's great for the A team players knowing they have some sort of an incentive and knowing that if they play well, then they'll be called up to the senior side.
"And the coach has sent out a clear message to everyone. If Scott can get dropped then so can anyone.
"But he'll be looking to come back and all of us will have to raise our game to make sure we stay in."
Hines comes into a Scotland set-up which has endured a disappointing start to the RBS 6 Nations campaign where they have suffered two heavy defeats in a row against the Irish at home and then the French in Paris.