"If I say Cliff can beat Bruce Lee up, he’s a fictional character so he could beat Bruce Lee up. The reality of the situation is this: Cliff is a Green Beret. He has killed many men in WWII in hand to hand combat. What Bruce Lee is talking about in the whole thing is that he admires warriors. He admires combat, and boxing is a closer approximation of combat as a sport. Cliff is not part of the sport that is like combat, he is a warrior. He is a combat person."

From: https://www.complex.com/pop-culture/2019/08/quentin-tarantino-responds-claims-he-disrespected-bruce-lee-in-once-upon-a-time-in-hollywood