The whole "reasonable person" thing is so ridiculous, especially for an issue that's currently so polarising. It's obvious that there are reasonable people with completely opposing views on the sex/gender issue, but the government has entirely passed the buck so the police have to deal with it.
You might as well have a law saying "If someone complains that someone else has done a bad thing, the police should just consider whether a reasonable person would think it was a bad thing, and if so arrest them". In fact we could just replace all of Scottish law with that one law!