Then who would you expect would do it?

The question assumes I expect someone to cut a power cable between Australia and Singapore.

I don't.

In the event of Chinese move on Taiwan then if Tom Cotton & Co. have decision making power then it's possible but unlikely they'd be dumb enough to think perturbing grid power in Singapore might exert pressure on China .. but honestly, who'd actually be that silly?

It doesn't have to be the expected outcome to be a threat worth considering. Russian Roulette won't kill you five times out of six but that's still considered an extremely high risk.

I think we both agree then.