Only CPRN's solid offer to take over KDFC's classical format would have given Entercom the confidence to buy KUFX. CPRN's action cleared the way for Entercom to repurpose the 102.1 frequency for simulcasting to the San Francisco area that KUFX's South Bay transmitter couldn't reach.Two seconds after I posted that entry I reread that part and thought, "That's really dumb."
The fact that KDFC was one of the last commercial classical stations in an urban area suggests that the classical format at best wasn't making Entercom as much money as another format would. Entercom wouldn't have had any qualms about shuttering the classical format in favor of one more profitable, so it wouldn't have looked around for someone to take the format off its hands. It's more likely that CPRN found out, or suspected, that KDFC's classical format was on shaky ground, and approached Entercom. Entercom would probably have gone through with the format change for 102.1 without CPRN's offer, though.
For Entercom, what counted was acquiring KUFX. What happened to KDFC and KUSF was nothing more than fallout.
It's an historical oddity, by the way, that Entercom owns the two frequencies that most recently broadcast classical music in San Francisco: 95.7 FM (formerly KKHI) and 102.1.