the fact that UW couldn't beat Gonzaga (that's my own interpretation), Romar canceled the series. Gonzaga has won 8 of 9 against UW.

Here's a couple quotes supporting that, from different articles:

"It was the Huskies who cancelled the series following the 2006-07 season, after the teams had met in each season since 1997-98."

http://www.thenewstribune.com/2014/08/04/3316805/huskies-renew-basketball-series.html#storylink=cpy

Here's a quote from Few in 2009: “The series should start in Spokane because Washington canceled the series,” Few told SI.com. “If they want to do a home-and-home, that’s fine. If they don’t, let’s all move on.”

http://www.seattletimes.com/sports/college/college-basketball-gonzaga-coach-mark-few-mocks-uws-proposal-to-resume-series/

Gonzaga didn't cancel the series. UW did. That was very public at the time.