China's present goal is to prevent construction materials from getting onto (and rebuilding) that derelict, not to starve those Filipino soldiers stationed on that derelict to death.
If Beijing wants to see those soldiers gone, one or two YJ-83 missiles from a Type 22 missile boat would've been much quicker. But based on what we've seen WRT the various "interactions" between the CCG and PCG so far, the CCG has zero intention of causing death to anyone involved in the maritime disputes in the SCS.
In fact, the CCG is actually more disciplined and restrained than even the rebel's CGA.