I could be wrong but his was my experience, i lived in Vic had Vic plates and licence and came over here for a holiday and got defected for only being to low but had to take it through regency, (i assumed i couldn't get defected interstate too) regengcy went ova the car and slapped another 7 defects on it (f.....headsz!). 2 defect stickers got some looks tho haha.
I had to get it passed here at regency and then they were meant to sent papers back to Vic to say the car has passed, which they didnt and Vic cancelling my rego after the allowed 3 days, but me no knowing about it for a good 4 or 5 weeks. Might be different for nsw but i would think so.
P.S next time tell them that your leaving that day or the next morning and they usually will let u go!!
Hope it helps