But we aren't judging the man. Only the work.

I'm not sure that any good work of art needs context to be "legitimate". I'm kind of torn on that issue.

If the picture can't stand on its own, should then a context or explanation be something that elevates it to something else.

Someone is these last few days made the comment about Migrant Mother that without the context this would just be another photo. But is not the desperation, and beaten down expression on her face, plainly there, even without the background knowledge?

I think it is. And this elevates it above a picture that needs explanation.