That is true now but not then. See below:
Under United Television ownership, the station carried programming from the Prime Time Entertainment Network programming service from January 1993 to January 1995.[2] In the fall of 1994, United Television and Paramount Pictures announced the formation of the United Paramount Network, lining up independent stations that were owned by both companies at the time as charter affiliates
So sounds like the FOX acquisition was more recent and had no bearing on previous contracts obtained by Channel 45. So that makes sense now why they wouldn't be betting against themselves today but evidently Channel 45 has plenty of clout in the past to compete with FOX. I seriously doubt there is a high demand for Suns games now which might have prevented other local affiliated networks from putting in serious bids.
That might change rapidly though and be a major win for FOX. Especially with a young core like we have and rebounding much sooner versus what people thought.
The regional Fox sports networks didn't even exist then though. The local basic cable broadcast rights were on ASPN which was owned by Dimension Cable.
Anyway here is the list of all the local NBA broadcasters for the NBA. Only the Nets, the Bulls, the Blazers, the Kings, the Spurs and the Mavs have OTA broadcasts and none of them are exclusively on OTA.
http://en.wikipedia.org/wiki/List_of_current_National_Basketball_Association_broadcasters