Let's look at the picture.
First off, the concert was not held on the bus. It was held at a club called Good Hurt. Of the seven people pictured in the audience, three are holding cameras, not to mention the person taking the picture of the backs of their heads. If those people are representative of the audience, then half of the audience wasn't as much watching the show as photographing it.
This would not have happened at a Tull show in 1968.
On stage the three backup dancers were in a precarious position. Wedged together on a stage that otherwise had room for them to roam freely, each looks disoriented and claustrophobic. Lo Diggs himself seems to be addressing this. "Can any of us be truly free when there are dancers who can't move?" he might be asking.
Flanking Diggs are two men who don't appear to be helping him. On his left, in the red shirt, is a man clearly plotting Diggs' downfall. "I can do better than that," he is saying. "Lo is so musclebound that he can't turn his neck to look at the whole audience. I would look at the whole audience. Would that Fate intervene to let me show my skillz!" Despite his complaining, the conspirator is not using any choralography or the most basic jazz hands to engage the sides of the audience Diggs is neglecting.
On Diggs' right is a man wearing a Halloween costume I put together at the last minute for a party in 1999. I don't know where he got it, but he is looking directly at me, saying, "I've got your Halloween costume, Grams. What are you going to do about it?"
Possibly the most poignant part of the tableau is the empty hat and shirt draped over a microphone stand on stage left. Like John F. Kennedy's riderless horse in his funeral procession, the unused hat and shirt represent a fallen homie. That fallen homie is named Affordable Healthcare.
So as you can see, there is a lot more going on with a Seymore Butts Party Bus than just strippers.