They know very well how rebuilt Teslas risk of injury or damage are different? My guess is there haven't been hundreds of crashes or incidents with rebuilt Teslas or other EVs so there is not enough data to say either way.
Rebuilt cars in general. If they pass a road worthiness inspection, statistically, there is very little difference in safety.
Lots of people here have this assumption that Teslas are these super-difficult magical cars that are extremely hard to work on. That could not be further from the truth. Because of the simplicity of the design, they are FAR easier to work on (no exhaust, no transmission, etc.). People that rebuild these know what they are doing, and do things like inspect the battery pack, etc. before going for the rebuild. The great thing about the modularity of the design is that if the pack is damaged, you can get all of your pack cost back in most circumstances by cracking open the pack and selling the individual modules (again, TESTED - which is not hard to do).