Why would you post about not getting a response from someone within a window of time you see fit? that's dumb.

I contacted his agency (shanahan.com.au) for the best method of contact and they told me fanmail can be sent to
PO Box 1509
Darlinghurst
NSW
1300

And I received a surprisingly prompt response. I requested a PotC autograph and was sent one - it's clearly one of those mass-produced ones agencies keep around for such requests based off their original autograph but it served the purpose I was needing it for.

Hi Piratesamurai22

Thank you for your feedback

Did you include a Self Addressed Envelope?

Fanmail

Sent a letter, and a cell frame in a frame to Rush, this was the start of July, or end of June. Either way it's January now and I might have to assume he won't reply back, which I am saddened by. Sent from southern California