As I said before on this thread, I *really* don't think Salem's businesspeople are going to care about KFNN's format as long as the tower rent is paid on time. The talk show hosts and programmers might think differently, but they don't (usually) run the business side of things like this.
As to the station's coverage, the AM's daytime signal should be fine valleywide. While it no longer puts what I'd consider to be a city grade signal over Mesa, the station's city of license, the coverage of that town isn't bad. As to where the most politically liberal people live in the Valley of the Sun, the answer has to be Tempe, which is a pretty typical college town. Phoenix City proper has quite a large liberal population, especially downtown and south (you can see that by who the elected officials are). So while I think that the purchaser may have overpaid for the signal, I think that, during daylight hours at least, the signal should pretty well cover the liberal parts of the Phoenix area. And, of course, the company can always webcast that signal as it does with WCPT...