[JohnGalt]

All that really matters is he did not govern as a conservative when he was President and he did not campaign as a 'conservative' in 1912.

He supported every progressive contemporary issue of the day, and was a large reason not only Wilson, but the nineteen-teen governments unleashed the destructive power of the central government.

[William McKinley]

he did not govern as a conservative when he was President

In some ways yes, in others no.

and he did not campaign as a 'conservative' in 1912

Conservatives can run populist campaigns. Buchanan just did.