If the Republicans are more loyal to Russia than their fellow Americans, they can't speak of nationalism, nor can they legitimately criticize football players for kneeling for the flag. Even if Colin Kaepernick were to burn the flag on his front yard every day, there would be no grounds for criticism from Trump supporters.
If the next one up after Trump says Russia is bad they'll believe him, they go with the strong man. Romney was always right in that Russia is our greatest enemy, and Republicans agreed with him then too.
So they're willing to sell out their country for partisanship, even when that selling out pertains to illegal behavior. How is that different than what Robert Hansen did, or a government agent who passes secrets to Russia for money?
Because they're "real Americans." True patriotism is defined as whatever they believe, support, or oppose.