The child sees the father carefully turning off all the kill switches, before handing over the phone. The first thought of the child will be, “Oh cool, it’ll be really fun to play with those neat looking switches.”
On the side of every phone there is a button that turns the screen off, and, from experience with my kids, I know that after triggering that feature once (usually by mistake while holding the phone), they will be very careful with avoiding touching the side of the phone.
I have had my daughter playing with my Librem 5 for some time and she never touched or asked about touching the killswitches. The beautiful interactive and colorful images on the screen are much more interesting 