That seems like a weird request to me. Tell him he can have his PDF's in one specific folder and just keep them all there. I can't see any reason why he would need to have a copy in every folder. I guess if he likes looking at them to get design ideas then it might be easy to have them in the folder that he has open at the moment, but he could just have another window open for the PDF folder.
** This is all my personal opinion so take it as a grain of salt if you have a specific need for paste shared **
In the past I looked into the share to another folder permission and found it not to be what it appears. Turns out it makes a copy of the file in the shared location. If a user were to checkout and modify the shared version of the file it does not actually modify the original. You then end up with a modified shared files. So, then if that modified version is accidentally used in an assembly where the original was supposed to be it could mess up production.
It would be better to just make a copy of the file with a different name. The paste share should be a pointer back to the original. Then the engineers could put a copy in their working folder but they could only modify it if they had permission to check out the master. Then if they edited the file it would show up with the edited form in all the assemblies wherever the file was shared to. If they don't want it to work that way then they actually want a different file or part number.
For example: I created this text file in the first screenshot. I then copied it and paste shared it into the parts folder.
Next I checked out the shared version in the parts folder and modified it, then checked it back in.
The original file does not have the second line of text in it.
If one of his PDFs got modified and then accidentally sent out to a vendor as the original it would cause problems.
The only way to know that the file is shared is by the plus on the icon. There isn't a clear way to tell if it is the master or slave or where the other copies are. I stay far way from the paste shared tool and don't give that permission to anyone.
Clearly it is time to your HR department (or whatever acronym your employer uses) involved.
my thoughts as well