Bet Wally doesn't have either a start time or a quitting time. Dilbert needs to go into the CEO's office and use his computer to demand that the PHB show up at work at 4:30 a.m. until further notice...should do wonders for the PHB's temperament....
This actually happened to me on numerous occasions with one boss I had years ago. He really thought he was doing something special by letting employees leave five minutes early, but if he needed you to stay late it wasn't even an option - just an expectation. And by late, I mean 2 hours late and sometimes past midnight. I didn't stay there long.
Hmm, Dilbert should take a different angle, and not even show up for work the next day. When he shows up the following day, he should point out what the PHB said. When the PHB, expectedly stat's to protest, dilbert should point out that at the time the PHB said he could leave early for that day, it was actually the next day at their office in Elbonia so he was just leaving early on a corporate time scale.