Not necessary. A superior pilot can maintain a positive 1G load of the airframe, even while performing aerobatics.
https://www.youtube.com/watch?v=V9pvG_ZSnCc
Hahahahaha! I just KNEW that was what that link was about!
Bob Hoover.
What a great man. My brother, a friend and I got to talk to him for about 15 min at Oshkosh years ago...I was completely impressed with him as a person.
He chatted with us as if we had known him our whole lives, took pictures with us, and was so down to earth and funny it was a real blast and privilege.
We also got to see him do his Shrike Commander show...:)
Combat flying often involves negative G.
Cup holder has to be on a gimbal.