This is the whole issue. It's all so complicated. Thinking about it, I suppose it should have been obvious they can just yank comments from an altered source. Somehow I had the wrong idea that original top-level headers were left untouched. IIRC I may have even seen appended top-level lic notices in the wild. Thanks to your informative comments here, I now know otherwise. The thought occurs that OSS licenses are very much mired in du jour technology of writing code. If a future language supports metadata for code, such as history, I would think none (?) of the current batch of OSS licenses would protect the metadata.

I've been warming up to GPL flavors for a while as well now. I'm even careless enough (I seem to suffer from a tendency to "wrong think") to toss around in my head a re-evaluation of merits of non-OSS licenses as worker in this field. An unfortunate thought that keeps cropping up is that "big business and big brother the ultimate benefitiaries of OSS".