I do believe they are a little bit skewed in their timeline of having played this one from '72-'99. I see nothing about that bass that suggests any older than '76. I'd guess more like '78. But if I've learned nothing else from notorious bluegrass circles East of the Mississippi, it's to never argue with a banjo player. Just go on and think what you think, put the 5 chord in front of the 6min and let them figure it out the hard way.
It's such a cool bass, who cares what year? I'd be more interested in knowing which employee built it.