Very few Iranians travelling to Indonesia would be doing do in order to transit to Australia. Many Iranian nationals would have business reasons to visit Indonesia, legitimate or otherwise. They are also not preventing Iranians front coming merely changing the visa arrangements.
In any case you are assuming that the occasionally passport carrying Iranian would not be a legitimate asylum seeker, they may well be considering the political climate in Iran.
Most asylum seekers arriving at the moment are Hazara and Tamil.
Would an asylum seeker who arrives in Indonesia via plane be a legitimate refugee with cause to board a boat for Australia? Absolutely! It's not I'm illegal to seek asylum nor is it illegal to be 'picky' about the country you seek it from. Assange and Snowden are prime examples of this and now one questions why they didn't turn to the geographically closest signatory state.
Maybe your hypothetical Iranian guy has family already here and just wants to be with them. Every asylum seeker has a unique set of circumstances.
Father, as someone who has studied these issues in depth for over 3 years now, I can confidently say that what you don't know about this is a whole lot. Your distorted factoids seem to be just a cover for racism.