They are not after the customer's votes. They are after the worker's votes, and those of Wal-Mart's competitors.
The interesting thing is that Hillary would send back money. Apparently, she thinks the unions who are fighting Wal-Mart are of greater value to her than Wal-Mart campaign contributions.
You're right. I could just as easily have said "ask for the votes of their employees". I stand corrected.