They must continue searching the South China Sea they don't have enough evidence to not stop. They need to get the CVR and the FDR. I'm afraid if the stop searching near the point of Transponder SSR loss we will never find it and maybe something will wash up on a shoreline in Kuching or Vung Tau or like wise years from now. But it will be too late for any valuable data.
They need to run a test flight with B777 on their suspected turn back scenario with all ground stations radar etc checking their data, to eliminate or confirm their assumptions. Because at the moment they are assumptions only.
I hope the Chinese and Vietnamese keep searching the South China Sea we should support them as much as possible.