Except, people are more than supervisors. Maybe it's the vacation that he's been planning with his wife and kids for 5 years. You can just as easily make a rule like "To all parents: Family time is not work time. Not even a death at the office trumps that. No exceptions."

Why?

If for no other reason, to be with the rest of your employees, the dead fellow's direct co-workers?

Because it's the decent thing to do, and your other employees will appreciate it.