The fact Maxwell was able to get great ratings in spite of a lack of publicity was a testament to the show itself.
Last I checked, after WMMS had a series of billboards featuring Rover and Maxwell back in April 2008, Maxwell's show had NO outside visible promotion, no TV ads, no outdoor festivals, no 12-month calendars, no external website/social media haven under Max's actual control, etc. In fact, the only outside promotion Max EVER got since then was the infamous Metallica stunt (which he purposefully did to protest the lack of attention the show got). And even after all that... Maxwell STILL traded spots with Triv for #1 in key demos.
Yes, WMMS is smart to promote Cox. It would have been insane for WMMS NOT to do so... especially with the station's main attraction (outside of Rover), which is the Browns games. Cox needs the promotion to rebuild the listening base for the show, and he will get a ratings bump out of it. But again, it's a totally new audience to replace the old Maxwell audience. The station took an audience, blew it up, and started from square one. While I will never listen to Cox, I would have had an even bigger problem with WMMS had Cox been thrown out before the year-long grace period ended.
As for CBS, again, that cluster has been in virtual limbo for nearly two years. We know that CBS doesn't want to be here anymore, but the market's far too miserable to sell those four stations, and I can't think of a logical buyer for them. Then there's the possibility that even IF WNCX wanted to take a chance with him in mornings, top brass in NY could have said no.
If Maxwell never resurfaces in Cleveland, that's the fault of the market itself.