I think it is okay to jump, dance, turn and swivel/pivot while instructing a step class. However, as you mention in your question, it is very important that the class be safe, the bpm not reach unsafe speeds and be based on current exercise science as it relates to step. What is also important is that the transitions are well taught and performed in a fluid manner.
I’ve taught Reebok Power step where jumps, jacks and hops were used, taught classes where I’ve implemented step/floor combinations to make the class more fun.
Every step instructor has their own style of teaching and the participants generally frequent classes where the choreography is most appealing to them.
The bottom line for me is that the classes safe and fun.
Thanks for your question.