That's what IRONCLAD was all about. The problem being that the RN had to try and hold Malta and the shipping routes through the Indian Ocean. Operation HARPOON was the result of 3 RN fleet carriers being tied up in the Indian Ocean, and Operation PEDESTAL, which prevented the surrender of Malta, was only possible because Indomitable could be spared from the IO.
And yet the Japanese had how many thousands of miles to transit supplies to these subs? There were destroyers at Ceylon, too. I think the Japanese difficulties outstripped the Allies, such that the invasion wasn't necessary imo.