If you want, you can change how CT-66 is classified there -- please document that exception to the CT classification guidelines on the wiki page (https://wiki.openstreetmap.org/wiki/Connecticut/Highway_classification). However, I don't think it makes sense to do that, as it does not improve the map to have two short, equivalent, parallel routes tagged at a high level of classification. I think the classification guidelines as they are currently implemented is a more effective representation of these roads: CT-66 as secondary ("highways which are not part of major routes, but nevertheless form a link in the national route network") and the non-motorway portions of the NHS route as trunk.