Phelps, Kellogg's -- and a Boycott?

Breakfast cereal giant Kellogg's has announced it won't renew Michael Phelps' endorsement contract  because he's been photographed apparently smoking marijuana. Some are already arguing for a boycott of Kellogg's in response. Others are urging people to contact the company and politely complain. Given that Kellogg's apparently thought a prior drunk driving arrest was not a problem, endorsement-wise, there certainly seems to be a hypocrisy issue here.

Boycotts are notoriously difficult to pull off, and many more such efforts flop than produce meaningful results. But personally, I think I can live without Rice Krispies for a while. What do you think?