Air Asia agents are infamous for making up stories. Its their new policy to assign seats across the region.

I did not subcribe to express boarding nor did I select a seat when booking, however when I checked-in I was given a seat number which they claimed is computer generated. I was flying HKT-KUL on AK flight, so nothing to do with Indonesian laws.

From what I understand, you can now pay to select a seat online when you book. If you have not paid to select a seat, their system will assign you a seat at check-in which the agent has no control over.