I’m going to half agree and half disagree here.
I think yes, we have to have an open mind and not assume off the bat that the bunny is mistreated. I think that is fair. However we do know that generally classroom rabbits are not well taken care of. I think that we can generally make a statement that most people are not very aware and informed on how to take care of rabbits correctly. This is not a judgement but rather a statement based on multiple experiences.
So my suggestion, if you are really that concerned is to check it out yourself. Don’t need to ask questions yet. If the bunny looks well cared for, then you may not need to proceed further. If things don’t look good for example, no hay, Wire floor cage, abundance of carrots, only alfalfa etc. then I guess you need to decide the next step
This step would be much more difficult as you don’t want to come off righteous, judgmental, or an overall pain. Your goal is to either educate and or help and this is where you need to be savvy or you might also need to pick your battles.