It would be a redefinition of the term POW to classify people who clearly do not meet the standards spelled out to get this status as POW's.
You seem to be in favor of redefining terms, as long as they fall in line with your own view on the issue.
If they do not meet the standards spelled out for POW protection under the Geneva Conventions then they are going to be governed by our domestic policy that we establish. Since our Congress said these practices were fine, it was perfectly in line with both international and domestic standards.
If some other country does not like that, that is their issue, but we broke no laws doing it. I will grant you we lost the PR fight in regards to GITMO, but legally, I think we were on solid ground.
Yes, they are human, I am not sure anyone is trying to dispute that. However, everything that was done was in line with all legal regimes at the time.
As for being credible, I think you need to ask "credible with who?" We will maintain credibility with most nations, and the ones we might not have it with the odds are probably good in most cases that we were not going to have it begin with.
On a side note, I am glad that you agree that credibility is such an important issue however, which is why we need missile defense, and upgrades to our nuclear arsenal.