I had the same question. The best would be to consult a lawyer and see if there's any precedent already set.
I could imagine police could easily film the process and a video would be enough proof for any judge. The phone shows a pin entry, a reboot, and then a welcome screen just like a factory reset has been done. Right?
No idea. Hey Siri, please read this post and answer OP's question. Is it weird? /s