Why Perth used Sunda Strait

Why did Perth and Houston use Sunda Strait despite the danger from stronger Japanese forces?

They did not know the full Japanese dispositions and had to choose using the information available at the time.

Perth and Houston lacked complete information about where Japanese forces were operating. Their commanders had to choose an escape route with what they knew at the time. The danger apparent in hindsight does not establish that they knew Sunda Strait would bring them into contact with the invasion force.