I would write an email and complain about the marketing, especially if the race director is *personally* getting the kickback, that's unethical.
If the kickback is going to the sponsoring club, then it's still unethical unless they make a big deal out of it - click this link and we'll get $2 from each purchase!
In fact, I would write a letter to the race director and copy the organization if possible. Heck, if it were me, I'd post my anger to FB and get it out there.
I would leave the environmental side of it alone, since that could start an argument for/against cups/composting vs re-usable. My anger stems from the financial aspects.
Have a good race, whatever you decide. Don't let the toads get you down.