I think it's kind of ridiculous to then blame the regulators for the fact that Microsoft decided not to go ahead with a more competitor-friendly design.
The fact that Microsoft abandoned it as soon as a regulator pointed out how anti-competitive the design of the API was makes you wonder what Microsoft's true intention was. To me that implies the anti-competitive design was its main feature and to Microsoft it would've been pointless to continue without it.
Maybe. Not working at MS I can't say what their reasons were.
But another way of looking at this would be that perhaps they wanted to be the beta testers of the API themselves because opening it up would have been a maintenance liability for the company. Microsoft tends to be pretty good about backwards compatibility in ways that Apple is not.
We also don't know that these APIs were cancelled, they may make it into future versions of windows.
The fact that Microsoft abandoned it as soon as a regulator pointed out how anti-competitive the design of the API was makes you wonder what Microsoft's true intention was. To me that implies the anti-competitive design was its main feature and to Microsoft it would've been pointless to continue without it.