The cable system in my hometown of Cedar Rapids (IA) was always changing hands during my youth. I think Mediacom has owned it the longest. It was previously owned by Cox, TCI, and AT&T Broadband. I am surprised Comcast did not take the Cedar Rapids cable system over like they did the AT&T broadband system where I live now (Springfield, MA).
Maybe Comcast does not want to serve rural areas like Iowa. Probably the only major service provider that would take over Iowa cable systems would be Time Warner. Time Warner is the dominant provider in Maine, which is rural like Iowa except they have large forests of pine trees instead of open cornfields. Massachusetts is pretty urban except for the western part of the state outside the Springfield metro area.