Because unfortunately right now, a computer can be considered a third-party device.
And how does that violate open access? Does VZW provide a way to connect your computer? Is there no VZW-approved method and plan to connect your computer to their network? Why then would you assume VZW has somehow violated the spectrum guidelines?
Open access says nothing about how VZW must structure their plans or offer the service. It specifically leaves the door open for pricing options, and that's exactly what VZW does. Just because you don't like separate plans for smartphone data and mobile broadband data doesn't mean VZW isn't compliant.
VZW opposed the spectrum guidelines most likely out of fear of losing some control over devices they approve for their network. Further down the road, most likely because when everyone is on LTE people will be able to switch carriers while keeping the same phone as they please.