I believe this company would be just fine with someone being an eBay only reseller (as long as you can provide proof of being a business). They will want to know your ABN number and registered ABN name. If you aren't an official business yet, and let them know your're an eBay reseller interested in getting set-up then you probably won't get far. When I contacted them they said it would be fine to resell on eBay, Amazon or even Facebook (as long as you're a business). Of course, companies sometimes change their policy towards their attitude about reselling on eBay/Amazon but based on my experience with them previously, I think eBay only resellers would be welcome.
I hope that helps to clarify but if there is more information I can provide, just let me know :)