A diminished interval has one less semitone than a perfect interval. Since C to G is a perfect fifth (7 half steps), C to Gb would be a diminished fifth (6 half steps). Since C to G is a perfect fifth (7 semitones), C to Gb would be a diminished fifth (6 semitones).
Well the food could've been bad and he probably didn't get enough business or the workers could've been rude or even the cleanliness could've been horrible. Or he could've just wanted to shut it down.
