I am unsurprised that Bishop won, although I will admit to disappointed. Certainly not to despair. I've lived in NC for over four decades. If I were to despair whenever a Republican won something I would have left the state or offed myself long ago.
As you say, it is an historically red district. In what has become, through chicanery and outright cheating, a red state.
But Bishop squeaked by with barely two percentage points. On what amounts to a bye election with the full weight of the national GOP apparatus bearing down on that tiny district for a month, and the demigod/ruler of the party making a personal appearance at the last minute.
Two points. This is not the behavior of an historically red district.
I'm not sure what technically makes a district a swing district. But a two point margin after over half a century of being solidly red has to come pretty close.