It's a fine enough use of "obviously", and they don't mean it from a legal standpoint. If you were an editor of the article, you could probably have convinced them to change the sentence to say "…obviously not a copying issue…" instead of "copyright infringement" or some other nuanced edit. This is nothing more than being super picky about the exact wording in one sentence.
You make good points, and I appreciate your response, but I think the issue goes deeper than the wording. If your reading is true, then I'm bothered by the complacency of the author in allowing the reader to conflate the legal and the logical. If this were an editing oversight, it's forgivable; but as a rhetorical strategy I find it deplorable.
While that may be a fine enough guideline, there certainly can be judges, even on the SCOTUS, who argue against what is "obvious".
Sure, but given the manner in which Supreme Court cases are chosen, it's exceedingly unlikely that a case would make it to the level of the Supreme Court unless there is something non-obvious (or at least disputed) about the matter.
Reductio ad absurdem: if a law is passed saying that it shall be considered "homicide" if a fiction author describes a murder in a book, it would still be perfectly sensible to say, "that is obviously not homicide".
And if a law is passed that says a drawing depicting a tentacled monster having sex with a cartoon child is legally classified as "child pornography" is it also reasonable to say that a cartoon is "obviously not a child" (http://ansuz.sooke.bc.ca/entry/335)? Possibly, but it would be disingenuous for an expert on that topic to do so in an article discussing that exact legal debate in a manner that is likely to mislead the reader.
The only weird part of their sentence is that "copyright infringement" is a legal wording, and they were using it to refer to the concept rather than the legal interpretation.
I think it's a conscious strategy rather than a weird detail. The fashionable term for this sort of approach is "motte-and-bailey" (https://philpapers.org/archive/SHATVO-2.pdf), and involves intentionally conflating two concepts, one which is easily defensible and one which is not. The base question for me is whether or not the author is consciously using a rhetorical strategy that involves misleading the reader, not with whether some degree of simplification is always necessary. It makes me doubt the strength of an otherwise reasonable argument when an author intentionally adopts such a strategy, and I think Doctorow is a good enough author that I start with the assumption that the rhetorical effect is intentional.
> arguments about this have shifted
Only in a Motte-Bailey sense .
PM: "77 cents to the dollar, it's a crime!!"
DO: "That's complete BS".
PM: "Well, you're right, here is more reasonable data"
DO: "But that doesn't actually show a gap"
PM: "Oh my god, 77 cents to the dollar!!"