I suspect the rule to disable URLs has nothing to do with what you are seeing: that feature has nothing to do with or impacts attachments or attachment types.
The most likely answer is that the attachment really IS a ".bin" file, based on SMG's true-typing of the file attachment.
Based on the attachment name, it looks like the original message didn't have the file name specified in the relevant mime part, so SMG generated a name for it while scanning. The PDF icon, is likely an artefact of your mail client (SMG doesn't insert or generate any "icons" or "images").
Of course the above are "best guesses" based on what you have shown us here. If you want/need a more definitive answer, you should open a support ticket and submit the email as evidence.