Speaking as a Maria fan, I think it would have been nice if she showed some concern for her opponent. I think Maria could have at least gone to the net and expressed some concern. Then, she could go back and warm up. I don't think a moment of compassion would break a player's concentration. But, I don't think this is the crime of the century. In some ways it is actually better than feigning concern, which many do.
It was an error in judgment. It happens with everyone. Let's see if she learns from it. I am still a fan.
As far as the bathroom breaks - simple - change the rule. The rules allow a lot of leeway and the umpire allowed her to go. I once saw Kournikova request a bathroom break and it was denied by the umpire because Anna was trying to stall because it was getting dark, and maybe she could get off the court and regroup overnight. Here, the umpire should have put her foot down, and if she can't, then the rule needs to be changed. I mean, think of Pierce in the USO semifinal. Why do they have a rule that allowed her to take back-to-back injury time-outs? Change the rule.
There is so much at stake now, players are going to look for every advantage if they are allowed. This is a sport, not a garden party. All champions have a little ruthlessness in them. This is what makes them champions. Some are just smarter about keeping up appearances.