As everyone is saying: just don't let it on the network. It's a little annoying because you can't have smart home stuff like "turn off the TV when I leave the house" working, but that's it.
My thing is, don't use an Apple TV. For the last 15 years or so I've just used a Mac Mini plugged into a big TV, and it's perfect. Get a wireless keyboard and trackpad and one of the many available trays that will hold them together. I'm literally typing this right now on this exact setup.
It should mostly work with HDMI CEC. My Android TV (Nvidia Shield) will turn my TV on and off. I only use the LG remote to adjust the volume although if you're using an AVR, it should do everything.
you can let it on the network, just block it from leaving the network. Lets you have the remote control features but without the risk.
Better hope that no guest connects the TV to their phone hotspot to watch their Netflix like one user in a previous post reported happened to them.
I recommend turn off tv via home automation involving smart plug thingy, and tv set to turn on on each power cycle return