The pupils of the old man dilated when he saw the spear coming at him. This wasn't a spear created by just Reynolds, as soon as the spear made contact with Grey's icy flame domain, the tip was reinforced, further strengthened by it. Not just that, but Klaus' initial attack also merged with the tip of the spear.
The old man wanted to move, but he knew it was too late. If he tried to shuttle through space, he would be struck with this attack which is very dangerous for him.
The spear hit the film, and just as everyone expected, it wasn't repelled by the old man, rather, it broke into the old man's space, heading straight for his head.
Reynolds went for the kill.