Which Buddy or Mate have you been listening to now??
There is a lot more logical thinking behind Indonesian cabotage laws than you give them credit for. (Also some illogic, like passing laws that Indonesia don’t have ships to meet)
To reserve domestic trade for Indonesian flag ships, Officers and Crew is fairly logical, as long as they don’t mix other things into a Cabotage Law…
Since Indonesian seafarers work on all kinds of ships and all over the world, they KNOW that there are differences in pay based on nationalities. (Not always corresponding to abilities)
I have NEVER heard of any such rules.
PS> I worked in Indonesia well over the age of 60.