The built-in PDF reader never catches the title of the document anyway, so at times it gets really annoying to save documents with a reasonable filename.
The behavior in PDFs is consistent with the behavior in web pages, so I think if we decide to change it, we should change it everywhere and not just for PDFs.
@mzlink sorry, I didn't mean to say you should know, I only meant that this is the same behavior across web and PDF.
I think it is by design because the context menu is different depending on what it targets. If it targets the whole page, you have menu items related to the whole page. If it targets a selection, you have menu items related to the selection.