Why not fix all the typos if it's as easy as clicking 'edit file'? He has the option to merge it by clicking one button.
I just can't see the downside. He didn't want to merge it due to the lack of signed-off-by, but at least he knows there's a typo there now and can fix it or let it be if it doesn't bother him.
(For the record, this was not the first typo fix contributed, see https://github.com/torvalds/diveclog/pull/2 for something he already pulled in.)