What I don't get is when Indians try to make it seem like they could blockade us, and we wouldn't do anything in return.
As for the flags of convenience, if you attack a vessel with a flag
other than a Chinese flag (which will be most of them given how international shipping works), that is an act of war upon the country which the ship is flagged with. And if you try to blockade all the ships indiscriminately, the entire world would come down on you for it.
More importantly, India would have to be prepared to win a full-scale naval battle with China. Not only taking on the vastly larger and more powerful Chinese Navy, but having to contend with the world's largest arsenal of sub strategic (non-nuclear) missiles being constantly fired at the Indian Navy, and at the Indian mainland. Especially considering that Delhi is so close to the Chinese border, it is even within range of conventional rocket artillery.
How many DF-21D can your Navy absorb?
At most, India will be able to interrupt a small percentage of our oil supply for a month or so, and our strategic reserves will cover that. Not to mention our vast reserves of domestic oil, more than even America has.
This small interruption, in exchange for your ships being hit by DF-21D? In exchange for all your airbases in NE India and even Delhi coming under fire from the largest conventional missile arsenal on the planet? In exchange for what would undoubtedly be a extremely strong conventional response from the PLA over India's land borders, possibly ending up severing the entirety of NE India away?
The only Navy that could blockade us is the USN, since they are the most powerful Navy in the world. And even if we couldn't break the blockade, we could sit back and hurl DF-21D and take out their ships from thousands of kilometers away. In the end, our missiles are far cheaper and far faster to build than the targets they will be destroying, is that really worth it for a blockade of a few months, which is already covered by our reserves?
You'll have to decide if your ships and soldiers are more valuable and easily replenishable, compared to our mass-produced missiles.