Harrison is talking specifically about the new light rail going up in Minneapolis. He argues:
"Building a barrier down the center of a street cannot be good for business. When driving, the only way to access the vast majority of the businesses on the opposite side of the street is to drive a distance to the next major intersection, then make a (probably illegal) u-turn and drive all the way back. Given this choice, most potential customers will bypass the business, and some may choose to stop at the competition on the convenient side of the street."
He also argues in favor of personal rapid transit (PRT) instead, and that pedestrians are unlikely to take to the light rail in the winter when temperatures dip below zero.