In my view it is not a validation but rather symptomatic of an outcome and effect from a regime that is used to getting its way by fiat and damn any opposition because they are either suppressed, censored, sent to education camps or imprisoned. China simply extends the way it behaves domestically to the international environment and finds itself misplaced in articulating defences since its actions are not founded on logic, reason or international norms but rather shaped in its outlook through the lenses of uncontested domestic audience. As such in international interactions rather than articulating its policies, China finds itself at a loss in explaining its actions and customary have to resort to statements of anger at others. This state of affairs just cascade down to its surrogates i.e. the fanbois.
I think he's saying it's "validated" in the sense that just as nfgc accuses others in the discussion of "simply close[ing] their mouth, or turn and walk away, or declare by fiat that the discussion was over," when he is presented with a series of counter arguments he also chooses to ignore the ones he wants to. I personally think there's nothing wrong with avoiding an argument if one wants, but if you're going to criticize someone else for doing so then you'd look a bit like a hypocrite
In the same way, the analogy which I think Joshuatree is referring to, is that other claimants in the SCS such as Vietnam had conducted construction and reclamation of their occupied islands and outlets initially during the late 2000s before China did, and then when China decided enough was enough and began its own larger scale reclamation and construction in the early 2013, the nation which threw the first punch and other nations who did not criticize the nation for throwing the first punch are now directing all of their attention almost exclusively to only China's construction activities.
At least, I imagine that's the kind of analogy Joshuatree is referring to. The exact accuracy of it is another matter.
I actually think this entire vein of discussion is regrettably juvenile.
The way in which these SCS threads with nfgc go usually is that he presents an exaggerated, stereotyped (and sometimes with tinged with hint of racism) remark about China's actions on the geopolitical stage with the often unspoken conclusion that China is therefore Asia's or even the world's biggest a-hole. Or that at least, China is the biggest a-hole in the SCS dispute.
This naturally ruffles the jimmies of a whole heap of people on the other side, who would bring out what they see as counter examples, including context, the activities of other claimants, and the activities of other nations in history to demonstrate that in their view, China's actions are hardly unique and are in response to the actions of others and that other nations in the geopolitical domain have acted in greater a-hole manners than China.
But nfgc will then insist that those are just excuses, and that China is the single biggest a-hole. The other side naturally argues for the opposite.
Rinse and repeat.