That is not quite true since in that case the files are locally stored. A retrieval system would be what AirServices already has in place for us - a means of retrieving (downloading) the files to a local storage area. What this rule is supposed to prevent is other people putting these files up for download from an alternate server.
This, I imagine, is a means of controlling the distribution rights of the files, much like in that you can only get official i-Device Apps from Apple's own servers. They are, after all, copyright of AirServices Australia.
Also not quite. I don't know about the "commercial person's" situation but the fact is the files are available for download as .PDF. If AirServices didn't want us to download them, then they would've published them in a different, non-downloadable format.
Cheers all.