I watched it all and found it quite interesting. The change to court size was odd and had more consequences than just giving Sabalenka a smaller court. It definitely made Kyrgrios take pace off, and if course affected angles. Sabalenka was serving from well behind baseline to compensate for change. Kyrgios not your average mens 675 in world and mixed it up so much it was totally different to most women's, or mens matches even. The one serve each was more of a disadvantage to Sabalenka if anything and she lost quite a few points on faults. Presumably Nicks normal second serve still has quite a bit of pace on it as well as the spins. Annabel Croft was saying Sabalenka should have had 2 serves and Kyrgios only one....would have made it even more pointless. I don't see a problem with men playing against women at lower club level, eg our club has singles box leagues like that. There clearly are loads of people playing where women can beat men. Or young juniors playing boys v girls at under 8/9/10 at lower levels.
The girls have to play with the boys because there just aren't enough girls entering tournaments. There is still a male advantage even at 6 years old. It takes an exceptional girl to be able to compete against boys and then, because some of the girls aren't good enough to beat the boys or even compete, atleast occasionally, they stop playing.
Theoretically box leagues should be fine because the movement upwards and downwards creates a system whereby the players should be evenly matched but there will be Women that opt out because they don't want to play Men, you just won't know about them because they'll just disappear off your radar.
Not tennis related but I used to play Squash and entered the boxes. I had to withdraw in the end because it was dangerous for me and that then led to me no longer playing because there weren't enough Women playing. It wasn't the good players that were an issue, it was the lower level players who had no awareness of where I was and would literally throw themselves around and at me to get to the ball. Now granted there isn't the physical danger in Tennis because there is a net separating players but there will still be Women that walk away because getting the ball served at you or hit at you with the power that even bog standard Male players can generate isn't actually that much fun.