I don't know what all the fuss is about on using ATF in aircraft brakes. The O rings are compatible with petroleum based oils. ATF is such; any hydraulic oil will work.
I have been using ATF for over 40 years. An engineer friend used ATF in his 310 Cessna for 35 years. I probably have close to 4,000 hours (different airplanes) using ATF in my brakes. Never had a problem! Thank goodness for experimental aircraft.