Good try, but no. That in no way says that there is no other possibility that a mid air. But if that's the inference you drew from that, next time, rather than try turn a phrase, I'll spell it out for you in small words in legalese.
He didn't know what he didn't know
Yep, totally right. He didn't. And he didn't either wait around to see what the result was, nor did he ask FIS 5 what the result of his inquiries about and airways clearance was. He had a previous instruction to wait OCTA, which seems pretty self explanatory to me. He never once entered an orbit or held, he just got close to the zone boundary, decided he couldn't be bothered either doing even a single orbit. And rather than ask FIS 5, did he have any further information about the possibility of a clearance, he called up FIS 5 and said, don't worry about it, I will resume my previously planned route, and no more was spoken of it. So, there were many possibilities to find out what he didn't know... Waiting a minute. Asking for more information.
As for the Wx at Williamtown, I don't have the exact file with me (on my other computer back at the room, so If I am wrong, I will cheerfully retract) but, IIRC, there was some scattered cloud in the zone, and strong wind but still VMC. There exists the possibility for a reduction of visibility for the 'See and Avoid' principle.
But, I note you didn't address the most pertinent point, it was the PIC decision to do what he did, when he did it, and without obtaining all relevent information, and not the fault of the RAAF and it's conspiracy to hoard all the airspace it can.
You have also not given one single shred of evidence that supports Dick's position that it was all the RAAF's fault.