Earlier quoted context omitted.
This argument might make you feel better, and it sure sounds sympathetic, but it doesn't change the fact that Nader's hopeless campaign gave the election to Bush. It's not as if the concept of spoiler candidates is new to US politics; it's how we got Clinton, the President in office at when Nader ran!
The argument that a vote for nader is a vote for bush is flawed. The basic premise of voting is that you vote to support a candidate and or a set of ideas you align with. Its a step better than voting "none of the above" as it provides an idea of what you would prefer. The concept of voting for the "lesser of two evils" just further perpetuates the mess that we find ourselves in today.
I've always found this video a good explanation of the problems of our voting system https://www.youtube.com/watch?v=s7tWHJfhiyo