We had this question "Should a link validator report 302 redirects as broken links?" over at webmaster pro's recently. I can only guess at an answer, but based on the OP's findings the stackbot regards 302 redirects as broken links - is this true, and is there a reason why?
No, the link validator will continue crawling the chain (up to 5 levels deep), if it eventually leads to a 404 or 500 or whatever that is not 200 the original link will eventually be considered broken.
We are considering doing a blanket "community" update on 301s, so users don't have to wait extra time when they click on links and so when the perm redirect is gone we still link to the content.
Overall redirects are heavily misused on the Internet, often people really mean 301 when they use a 302 sometimes they mean a 307.
Additionally a big offender is US, most of the time internal links do not link to the canonical URI on our site so they go through a redirect. We should fix that on post save (at the minimum)