This is only for TVs running Roku software
AFAIK no Roku set tops have an ATSC input, so all they could do is tell you what's on broadcast TV - not actually let watch it! There aren't any TVs running tvOS, so integrating broadcast channel guides in this way would be pointless for Apple. The article is truly comparing apples and oranges.
Not sure what Apple's failed deal with Comcast would have consisted of. The Apple TV would have required a QAM input to connect to Comcast's cable system. Without that all it could have done would be to act as a "client" to one of Comcast's whole home DVRs. Not sure what Comcast charges for those, and if paying $150 for an Apple TV would have had payback after a few years of not paying Comcast monthly fees.