Every action produces an equal, opposite reaction. Cut the barrel short, expect unburned powder out the front.
Doesn't matter what kind of can he was using. It's a known, bonehead-move in the long run with a 338. If a suppressor DOES handle it for a while, that suppressor will be screaming for you to STOP IT each time you pull the trigger.
Not a gamble I'm willing to take, suppressors being so hard to own.