I think the problem with listing specific safety concerns and then saying "yeah, well, but even a clipped bird MIGHT do that" is missing a fairly key point. IMO the main contribution of clipping to safety is that
you can keep track of where the bird is a limit/monitor the hazards within range much more easily
Take the toilet example... if I am in the bathroom with Scooter and a guest has left the toilet lid up, for one thing I'm going to see the hazard as soon as the bird is in range and for another I'll be right there to rescue him if necessary. If I'm in the office/bird room with him sitting on top of the playstand, he could get as far as the door to the hallway on his own via air, and I suppose if I really wasn't paying attention, he could walk into the bathroom from there, but he wouldn't be able to get up to the toilet, so if the toilet lid were left up it would be pretty unlikely he'd manage to get in there. If he were flighted, he easily could without my being aware of it.
It's not that clipping renders the hazards safe, it's that they allow you to keep track of where your bird is and to control the bird's location and monitor the presence of hazards in the vicinity much more tightly even when the bird is out of cage.
You are trading a measure of freedom for a measure of safety. No absolutes here.