You've sort of missed my point here: the point isn't a direct military engagement with China, and the Millenium challenge war game wasn't about a direct engagem

You've sort of missed my point here: the point isn't a direct military engagement with China, and the Millenium challenge war game wasn't about a direct engagement with a major power - it was about an invasion of a regional state like Iran. So the whole issue is that the US getting embroiled in a fight with someone for reasons has the issue that they're unlikely to be in a full-scale war footing, but rather they'll be fighting a single state with lots of neighboring friendlies, civilian traffic, and since they're not directly fighting China, no one's going to be able to stop the Chinese if they choose to screw around from backing whoever the opponent is. Basically: exactly the scenario Russia finds themselves in with Ukraine.