A canoe like this one is designed for paddling by two people -- in which case, the stern seat is the one that leaves little room behind the paddler, and the bow seat is the one that provides ample foot room for the bow paddler -- in this canoe, the seat very close to one of the thwarts, which will be behind the bow paddler. This leaves the weight of the paddlers fairly well balanced.
However, when the canoe is paddled solo, things change. To trim the canoe well, you want the weight of the one paddler more to the center of the canoe. The seat that had been the bow seat for tandem paddlers becomes the seat the solo paddler will use -- facing in the opposite direction, so that the seat that had been the tandem stern seat becomes an unused bow seat. In this particular canoe, that thwart is very close to the seat the solo paddler uses, so jwil used a cushion to effectively raise the seat so he could sit with his legs over the thwart -- a clever idea. In many canoes, that thwart does not present such a problem.
If the solo paddler stayed in the tandem stern seat, the trim of the canoe would be poor -- it would be riding high, probably in the air, and even without wind it would be difficult to paddle in a straight line. With wind, the raised end of the canoe would be a weather vane and it would be very difficult to control the direction of paddling.