I would say that this is not a violation, but perhaps it should be. Perhaps a code revision is needed. As written, the code allows foreign pipes and ducts to be in front of the equipment, so long as a person standing in front of the panel has (I think this is the right number) 78 inches of clear space, measured starting from the floor level. But the code does not address the possibility that the equipment might be more than 78 inches high. The code does not address the possibility that a person might have to stand on a stepping stool, in order to reach something inside the panel. In your example, if a person had to work near the very top, the pipes would make the work difficult, and in my opinion, dangerous.