How safe are treadle feeders? Nothing is completely safe but as one poster said, the inward swinging door is safer than the guillotine style feeders like the Grandpa feeder and the Chinese feeder (and I sell that kind as well but warn people). We have a saying Oklahoma "Farm animals are never really safe around moving machinery and state senators."
Where you can really mess up with a treadle feeder is trying to mount it up off the ground. That treadle has to bottom out on something so it is stable to prevent a bird from slipping off and getting its head trapped in fast moving door. Normally birds are very quick at sensing the door closing and can get out of the way if they aren't on the treadle but when falling, all bets are off.
The thing is, not having a feeder that will keep the rats and wild birds out is also unsafe, far, far more unsafe as the vermin can bring in disease and parasites that can also spread diseases.