People's sexual orientation is not defined by what they do to themselves. Having a machine fucking your ass is no different to playing with your cock and wanking off.
Imagine having that chair on your front porch. You could have pants with a hole in the ass. Sitting on the porch watching the world go by with that machine pounding away.🤪
Receiving pleasure through anal stimulation doesn't make one gay. You can be straight, ie attracted to women, and enjoy anal stimulation. Don't be a prude.