Well lets see, Miller supports gay orgy parades, they add their label to insults against Christians, support illegal aliens flooding across the border. I think the connection to Move-on is quite clear; The company is run by a leftist moonbat!.
Given those facts, that would be a reason to consider Miller to be leftscum. The fact that they also use an ad agency that has leftist clients might be considered as supporting circumstantial evidence, but of VERY little weight!