Why would you go to Spokane to get to Pullman. Pullman is far South of Spokane.
Because you spend the night in Spokane which is a large city with many good hotels . Pullman is a very small burg . I am just speculating, ask them.
Pullman is an hours drive from Spokane
My daughter is a grad of WSU, so I have been to Pullman. I would think that they are going to Spokane (about an hours drive to Pullman) because there would be more lodging opportunities than at Pullman.
The Apple Cup is a big deal around here with the two largest universities going head to head (Univ. of Washington & Washington State Univ.). So, lots of people coming from the West side of the State (Seattle area), across the mountain pass and on to Pullman in the East. The weather at Snoqualmie Pass was treacherous last night and I am assuming the bus driver was driving a bit too fast for conditions. The only news report I have heard about it said the driver thought he had hit a piece of icy pavement.
Because it smells better...