An article in my schools newspaper was censored because it supposedly would have created chaos in school (it was about how our ASB does not support the views of the whole student body, even though they try to--in a nutshell).
The student who wrote the article printed out the article separately and it ended up being passed out around school. He was called into the APs office and now his Editor in Chief position may be taken away.

I believe this is an infringement on freedom of speech. Anyone else?

Well he wrote at the bottom of the article that it in no way expresses the views of the school paper or that they house responsibility for this article.

I feel that he did not violate anything--it was going to be put in the opinion section--and it was not racist or sexist.

No matter where that person goes, he represents the paper. Whatever he writes, in the paper or not, they see his name and associate it with the school. He's also [un]intentionally using his position in the school paper to get readers.

Do you mean a legal infringement of speech, or an ethical infringement of speech?

Ethically, yeah, I'd say they are infringing on his inalienable rights (Meaning, rights that no body should be able to take away, school, government, otherwise).

That said. The school says what goes. So legally, I don't think he'd stand a snowballs chance in hell of it getting published. What he did probably violated some school policy, and he probably agreed to the policy at some point.