What do we gain by poking them right now?
Just laying down a marker WRT free navigation of the seas. And showing allies we are not dead yet. If everyone gets used to obeying the Red Chinese when they call out threats, they will eventually get what they want and call the shots.
Depending on how close the artificial islands are to the Red Chinese mainland, they could destroy any/all US Navy vessels with their guided missiles, they got so many. To include our flat tops, the aircraft of which have shorter effective range given we are using F18s to in-air refuel F-18s.