These Japanese options to deal with Chinese dominance of the South China Sea which potentially interdicts vital Japanese sea lines of communication are valid. But there is another option for Japan.
Basically, Japan can resist Chinese control by patrolling the South China Sea or move shipping lanes to the Middle East and points west to the east and to the south.
Of course, the former option does not overcome the ability of China to use their nearby assets to stop the Japanese from escorting sea traffic during wartime.
The options are certainly reasonable. But they must be combined with strengthening alliances with nations along the sea lines of communication who are themselves arming up in response to Chinese ambitions.
And a strengthened Japanese submarine force to operate in the South China Sea to blockade China in response to Chinese strangulation of South China Sea lines of communication would be a useful complement to defensive efforts.
Sure, technically that violates Japanese constitutional prohibitions about offensive military weaponry.
But sometimes you have to go on the offensive to defend yourself. Because ultimately the distinction between "offensive" and "defensive" weaponry is silly.