I was about to get the Nulon Automatic Transmission Treatment but noticed it lists PTFE as an ingredient.

They list some great benefits about longevity of the transmission and smoother shifts, but i've read here that PTFE is not good for the engine.
Is this stuff ok to use in our tranny?

No, if you really need to add anything use the Shudder Fix, if your transmission is not having any issues why fix it if it is not broken. Magna Transmissions are very picky with what is run in them as you would know from research done on these forums