Completely agree. I'm not sure I see anything wrong with what the spammer is doing. He may be polluting the Pinterest 'stream' with affiliate links, but it's not like the people on Pinterest aren't on there just to look at random stuff they may never see anyways. Obviously he must be showing people stuff they want if he's making money on it.
It shouldn't even be called spam since every link on Pinterest is technically solicited. Every user on there wants to see new stuff, that's the point of the site. It's nothing like email spam that I didn't ask for, or junk mail that was sent to my house just because they grabbed my info from somewhere.