The sponsors are a business out to make money, not to make sound ethical decisions.

The way capitalism is supposed to work is that consumers (the capitalist synonym for “people”) avoid companies they don't like for whatever reason. The problem is this assumes consumers are reasonable.

The sponsor has little to gain by doing the ethically correct but publicly outrageous thing and standing by the innocent person, because there are more people in the angry mob than there are who would reward the sponsor for their sound ethics.