FCC passed a revision this past summer to the E/I rules - formerly, each channel and subchannel a station carries had to program three hours of E/I. Three hours on your Main .1, three hours on your .2, three on .3, on down the line. The new rule is a cumulative three hours (more if they choose, but three hours is the requirement) for the station, with one hour of the station's requirement being fulfillable by the station's secondary channels if the station so chooses and no requirement for secondary feeds otherwise.
So channel 42 or whatever has a mandate to hit 3 hours *total* now, and only an hour towards the requirement can be from programming on a secondary subchannel. Keeping the hour helps any stations that need or want Buzzr to help meet the E/I requirement, while they can now drop E/I that their affiliates largely can't use anyway.
The rules technically changed in September, but with it being a legal compliance issue and the old rules having been in place for years, plus whatever contracts Buzzr has had in place, I'm sure it's something that's been hitting in phases - with beginning of year being a good time for them to make the switch.
The handful of affiliates that carry Buzzr on their .1 mostly appear to be -LD and -LPs, which are sufficiently low power to be exempt from the E/I rules.