That does not seem like it would make sense in itself.
He could have got the same field of view by breaking two windows in the same room. He could also monitor his surveillance camera from his firing position. He would have lost that in moving to the other room
Having to move to two separate rooms did not seem planned to me.
He wouldn’t have the heavy draperies, which are only on portions of the windows, to help obscure him.
Sorry, I misunderstood your post at first. Some have suggested that he knocked out two windows so that he would have aim on the concert crowd from one, AND the airport, with the fuel tanks, at the other.
I remember one video that I saw/heard, where there were three distinct cracks - like deliberate sniper fire - and there was a suggestion that these were the shots that hit the tanks.