This isn't necessarily that strict of a regulation. They could require the sensor be on board but not actually regulate any of its usage. It could be a scenario like the Model 3's rear view mirror camera, where it wasn't used at all for the first two or so years and then later got a software update that started interacting with it. The important part is that the LIDAR unit is physically wired in to the system so that they can start using it in software whenever they feel like it's necessary.