The cable operators have no license to any spectrum
Cable operators could and should have ensured that all user equipment was protected. This involves using quality coax - cable and connectors. It is likely that the 4 channels 66-69 (30 MHz) will not be able to carry any analogue TV. They may also have reduced capacity for digital muxes or internet. This is a very small restriction 30 MHz out of 600-650 MHz..
The cable operators have no license to any frequency - they have to remain inside their cables. The same problem will emerge if/when cable operators extend the top frequency used from 862 MHz to say 1 GHz. GSM and LTE using GSM900 frequencies will give the same type of problems in the 900 MHz band (880-915 MHz =GSM-upload).
They did not enforce the rules of fully shielded coax and quality TV's - when it wasn't strictly needed - but this is the cable operator's own problem - end of story.