It's worth asking if they'll scan it again, but I'm fairly confident they would continue to refuse to scan it even if there were no copyright issues. My recommendation might be asking someone else to scan the entire dissertation on their own. The catalog record indicates the dissertation has 61 pages, which is totally doable.

On a side note, I wish there were a more formal way to exchange favors with regard to locating documents like this. Many documents are basically inaccessible because they are in libraries which won't provide scans. A website where you exchange credits of some sort would be really nice.

Incidentally, HathiTrust has it, but it's not available for download. In addition to Harvard, Cornell has a copy as well. Might be worth asking someone at Cornell if Harvard is a dead end.