Where were your feelings when China and Chinese people were essentially getting killed and trampled on by many both from within and without?
I think we all remember 八国联军. And the many other invasions, incursions, and occupations from the Russians, Germans, British, Japanese, French, Italians, and Americans. But to be honest, of these eight offenders, the Americans were the least offensive. If we want to discuss historical grudges, America isn't very high on the list. You should really be going after the Japanese, the British, and the Russians. In that order.
Sizable pacifists movement? Where inside China? Are you serious?
You would be surprised to see how many Chinese citizens (mostly young city-dwellers) who blame deteriorating Sino-American relations on Xi, rather than on an America that is reacting very poorly to the upset of its global hegemony. There will absolutely be young people crying for peace if there is a serious conflict.
If China was just some lawless country they didn't need to go through legal means in the first place.
I would like to point out that everyone can pass laws allowing their military or coast guard or even citizens to do certain things when interacting with foreign nations. I would hardly say that passing a law to enable the use of force against a foreign nation qualifies as "legal means". As far as international relationships go, we all know there's no such thing as "law". Just as nobody gives a flying shit if an American intervention in Afghanistan was "supported by Congress" and therefore "took the necessary steps under legal means", nobody gives a flying shit if the CCG's actions in the SCS are "supported by the NPC" and therefore "taking the necessary steps under legal means".
And I don't recall ever mentioning the legality of CCG's actions...
Before someone decides to call me an American stooge, I will make my position clear. The Chinese claim to the SCS islands was supported by the USA immediately following WW2. IIRC a USN destroyer carried RoC officials to each island to stake claim. The current Sierra Madre was beached deliberately by the Filipinos following a temporary RoC retreat from their post at the island due to an oncoming storm. In effect stealing the island from the RoC. The RoC, being a bunch of toothless losers, haven't really put up a fight about it. However, regardless of PRC or RoC government holding actual control, the historical precedence of the Chinese claim is clear.