It may be the case that denial of free movement through the SCS, results in restricted movement world-wide on Chinese vessels.
It would be quite easy for the English Channel to be blocked. consider the impact on trade to Northern Europe.
Equally, Gibraltar was not acquired out of curiosity, or trying to avoid the straits of Malacca, Panama Canal? Suez?
Nope China's response is going to be carefully measured.
IG