Just as devil's advocate. You couldn't get much more synonymous with Nike as Lance Armstrong. They did, afterall, name a building after him.
This needs to be questioned, but many people like to befriend and surround themselves with people that are considered "successful". From presidents to the heads of the IOC, and especially sponsors, people love to be seen with champions. If we now prosecute everyone through guilt by association with Lance, we will have to paint all of them with that same brush.