The only strange thing is calling it a Grand Slam," Kokkinakis speaks out on US Open mixed doubles

The US Open mixed doubles concluded yesterday with the victory of Andrea Vavassori and Sara Errani over Casper Ruud and Iga Swiatek.
However, the scheduling of this event before the start of the other draws, the change in format, and the participation of singles stars have raised questions about the seriousness of this Grand Slam title.
For Thanasi Kokkinakis, Australian Open doubles champion with Nick Kyrgios, this tournament should not be considered as such:
"I think there's always an asterisk regarding mixed doubles in Grand Slams. No one really trains for it; players just pair up and play.
But maybe I'm a bit bitter because my record is 0-10 (laughs). The only strange thing is calling it a Grand Slam when you win matches 4-2, 4-2. That doesn't seem right to me.
If they are so "equal" why can't their tour stand on their own again...?