...rebel flag (i.e. Confederate Battle Flag; "Stars & Bars") all year long "to honor the ideals of Southern culture", his motives might be suspect.

His motives wouldn't be suspect at all, unless he was an idiot & didn't know what the flag represented. His disingenuous excuse, however,- "to honor the ideals of Southern culture" (presumably these ideals include support for chattel slavery, white supremacy, armed attack on the United States Government & etc.)- would indeed be suspect.