It's a race bike which by definition means the only rules/regulations are win and don't get caught cheating.
It's not about the materials used to make it, it's all about being a machine made to race and WIN, as Innes Ireland said:
'I'd always believed that Colin [builder of Lotus race cars] was close to genius in his design ability and everything, if he could just get over this failing of his of making things too bloody light. I mean, Colin's idea of a Grand Prix car was it should win the race and, as it crossed the finishing line, it should collapse in a heap of bits. If it didn't do that, it was built too strongly."
-Innes Ireland