K.M.
Are you familiar with Operation Christmas Child (samaritanspurse.org)? Filled shoe boxes are sent around the world filled with toys and toiletries for different age groups. There are also shoebox projects for troops overseas (operationshoebox.com) and many others for specific regions. Tis the season to help box and wrap gifts for local purposes, too. If you get started with gift giving maybe he can collect boxes for a purpose, use them for some good and then start collecting again.
If he's an entrepreneur he could wrap the boxes so that they'll open (like in the movies) and sell them to friends and family - this would support the buying of more paper (on sale after the holidays) and generate some income. At least the pile would be rotated and he could keep collecting. Good luck - I can't wait to see what others suggest! :)