The gravamen of the issue here isn't that Milley spoke with the Chinese - no doubt there are protocols in place for regular contacts between superior officers in the U.S., Russia, China, etc. - and it isn't that Milley had a meeting with other high officers in the U.S. at which the protocols for the use of nuclear weapons were restated to make sure all were clear on them.
The gravamen of the issue here is that Milley colluded and conspired with Pelosi, and undoubtedly others, to improperly and illegally remove the sitting President - President Trump - from the chain of command for nuclear weapons (and perhaps in general), in violation of well-established rules for when and how the President can be removed, and he then utilized the meetings with other senior U.S. officers to implement that conspiracy, and conveyed the fact of the conspiracy and its success to the Chinese (along with who knows what else).
That is the gravamen here: the conspiracy/collusion between a senior military officer and a political opponent of the President to illegally and improperly interfere with the President's Constitutional authority as Commander-in-Chief.
