Sure, there is no ethical consumerism under capitalism. But I can do harm reduction. When someone says or does something shitty, I can avoid or stop using their product. In your example, if a road worker came out publically with some transphobic nonsense, I could raise that to my local road authority and they would likely lose their job. Are there more people that have shitty views in this theoretical? Maybe, but they will be less likely to spew them if they know there are consequences.
Adding to popularity does support them.