What you are advocating is the greater good theory. The theory holds water provided it meets three conditions : impartiality; agent neutral; and what is right. Unfortunately it fails in all three conditions in the subject matter of our discussion. For example, you take a healthy agent X against his/her will and organ harvest to save 5 terminally ill patient and argues that it is for the greater good that one individual sacrifice for 5 others. The problem is the benefit is partial. the agent is not neutral and clearly such action is illegal.
We have already beaten this to death. There is no ambiguity with FON. Its meaning is laid out in UNCLOS. China's view is in the minority group that had pushed for a different interpretation. That interpretation was rejected by the majority during the various sessions that preceded the final text as embodied in UNCLOS. There are two ways legally to change it. Revise UNCLOS through a full session of members or take it to the International tribunal
Can we please keep this OT
Frankly what has all these countries got to do with the current dispute? One of the institution provided by UNCLOS to settle such issues is the International tribunal but yet is rejected by China. There is a process and a framework as pathway that underpins rule of law. Outside that pathway is simply lawlessness.
It is greater good theory, but China's actions do stand your 3 tests for the greater good:
Test 1. "The problem is the benefit is partial"
We're talking about economic benefits suffered or gained, not directly taking a life.
But the economic benefits are in the trillions AND in countries where hundreds of millions of people are in dire poverty that this money DOES translate into large number of lives. Their benefit far outweighs the loss suffered by a few fishermen.
Test 2. "the agent is not neutral"
I think we're now delving into one of the fundamental cultural differences between Confucian societies (China/Japan/Korea/Taiwan/HK/SIngapore/Vietnam) and Anglo societies. Confucian societies are more hierarchial and focus on the overall health of the group rather than an individual. Therefore agent neutrality is not seen as a requirement for a greater good test.
Plus what neutral agent can credibly adjudicate in the SCS?
The Anglo principle would be that one should be judged a jury of one's peers, but who are the peers who have no vested interest in the outcome in the SCS? And international law on the seas is but what the biggest navy decides it to be, as any international relations student will tell you.
Test 3. "clearly such action is illegal"
Remember that Anglo common-law also allows precedent to be set and therefore it takes the pragmatic route of legitimising what actually happens in the real world.
There are clearly enough ambiguous territorial and EEZ claims that there is a genuine dispute.
Plus genuine differences in UNCLOS interpretation.
So again, where are the truly impartial agents that will judge, and by what cultural yardstick will they judge the greater good?
And in international relations, it really is the law of the jungle, as the US itself demonstrated by withdrawing from UNCLOS when it didn't like a judgement, amongst other actions.
At least until there truly is a world government which can censure the US or China, but that is a whole other discussion in itself.
===
How the US acts is important, because its actions DO set the benchmark by which China acts.
So it would be better if the US wasn't so hypocritical sometimes , but that's for the US to recognise and reflect upon.
China actually spends way more time thinking about its positions and making sure they are consistent, whereas even US politicians are surprised at some of the hypocritical crap that the US actually does in the background.
===
And I mention those other countries because you didn't believe Russia / Central Asia / Africa were neutral or supportive of Chinese activities in the SCS. I believe your exact words were "You are kidding, right?"
Think about it. China is now setting up a military base in Djibouti on the horn of Africa, as once again, the countries in Africa know that China has an interest maintaining the shipping lanes.
Flag follows trade, indeed.
I'll repeat again, Chinese trade in the SCS is essential to the Chinese economy, and the Chinese trade probably accounts for more trade in the SCS than everyone else combined.