You are again mistaking OK as "south". And "discipline" is not something I would call what happens here.Party discipline is almost absent from the south. Party leaders just don't have much control and don't use the control they have. Democrats know that if they kick that DINO off the ballot they'll never have a shot at that seat for another one hundred years. I'm not so sure about the Republicans.
The reality is that he was very likely exactly what he appears to be a Democrat in a Democrat controlled county. Probably a lifetime member, proud of his "Democratness" and always would be because his family has "always been Democrat".