Because escalation is risky. Things can get out of control. It's much easier to make a mess than clean it up, just look at the Middle East right now. Reality is not a videogame, you don't get any second chances. And for what? A worthless shoal? It is not strategically significant. It is not a high-value target. It is not worth risking anything for, let alone everything.
No, the patient approach is the correct way because keeping things slow and steady allows everyone plenty of time to think instead of getting into a foolish action-reaction spiral. And what do you imagine they're thinking right now in Manila? Be realistic here, nobody likes being pushed around. They are angry. They are upset. They are looking for options. The current situation is not working for them, so they need something else. Marcos thought moving closer to the US might give the Philippines leverage with China. It hasn't. The US already got what it wants (basing for a high-tech, high-intensity conflict), and their capabilities are not suited for a low-tech low-intensity one. Washington doesn't much care about some worthless shoal, and they are right, because it's worthless. Only the Philippines cares, because it is politically significant to them. Which gives China a pain point through which to exert political pressure. Which is what you are seeing right now.
So where does that leave you as the Philippines? Stuck between a rock and a hard place. There's a 052D at Mischief right now, doing nothing. Just waiting.
If you are the Philippines then you see it, and you know that escalation is not going to help you here. Escalate all the way up to a US battlegroup and the only thing you'll get is your own home destroyed. That's what it means to be a pawn of great powers. That's a no-win position. You, and everyone else in the neighborhood, will be thinking how much that sucks. And maybe, if you are convinced that being a pawn is not going to work out for you, that posturing about getting involved in a future high-intensity war is not actually going to help you out of the current low-intensity mess you're dealing with (and that's what really matters politically, because that's what is really happening here and now), then you won't do it. You'll sit on the sidelines and refuse to get involved. And if Beijing can slowly convince everyone of that, over the course of many years of low-intensity undermining the foundations of US force projection capability, then it will achieve high-intensity victory without ever firing a shot.
