There's a way you can address him directly without causing drama: defend him! "Hey Bob, I'm worried that the boss will think you're wasting time bogged down in

There's a way you can address him directly without causing drama: defend him! "Hey Bob, I'm worried that the boss will think you're wasting time bogged down in stuff he thinks are unimportant, and that your priority tasks get done by other people. I don't want you to get in trouble, we should figure out a way to avoid this."