I'm sure someone has and Smokin' could say,try it and let us know.
The butts have a lot of internal moisture and don't require it.
Memphis comp teams must inject-because the judge picks his shoulder off the cooker.
Many of us add a little of our rub,and maybe a small amount of Smokin's mop,when we pull the butt.
That way,you get accurate flavor and moisture. all thru the pork.
If you choose to,be sure you strain it well, to remove any large pieces.
Hope this helps a little.