Your "rules" don't make that list.

Except that #2 is one of the main avenues for my "rules." Military actions that comply with international norms do not result in trade losses. Military actions that violate international norms can result in heavy trade losses (hi, Russia!). So if you change the international rules so that more military actions are "okay," then that changes the cost-benefit equation.

#4 is a similar issue. Military actions that comply with international norms do not usually result in strong wealthy countries providing military assistance to the weaker country you've taken action against, minimizing your military losses. Military actions that violate international norms can result in everyone in the world trying to help the smaller country, whether by direct action (Gulf War I) or providing economic and military support to the smaller country (Ukraine). Russia's suffered vastly more losses in ships and planes (and men) because the rest of the world rushed to support Ukraine than if everyone had agreed that their invasion was justified.

So if you change the rules so that actions like this are more defensible, then you increase the likelihood that powers like China will use military force against their neighbors. Either because you have lowered the cost they will incur because of using military force, or because you have led them to wrongly think that the cost is lowered (ie. like Russia not anticipating that the rest of the world would rush to Ukraine's aid).

There's a reason why China has merely "harassed" Vietnam and the Philippine Islands, rather than moving in with the Red Army and conquering those lands. They are making efforts to stay "within the lines" of what will be considered an overt violation of territorial integrity that will arouse the wrath of the international community (a la Ukraine). Those are examples of the rules-based order working - it doesn't prevent "harrassment," but it does deter outright the type of outright military invasion and "war as an extension of politics by other means" tactics that used to predominate in the 19th and early 20th century.

The U.S. going back to gunboat diplomacy weakens the proscription against using military force to accomplish political aims (or criminal justice aims). By widening the arena for permissible military force, you make it much easier for China to use military force in their "neighborhood." Which is something we used to be making a serious effort to stop.