They sould do nothing.
From day one you and Oculus choose to live in a capitalistic economy, so don't be surprised if some people is trying to make easy cash. From day one we have concurred that getting easy cash from other people needs and whishes its ok and perfectly ethical.
Not that I like how things are...
What does capitalistic economy have to do with anything? You can have this with any economy, lol.
Anyways, they already have something in place - NO SUPPORT. Aka, people that buy those rift will be at the mercy of the reseller if there are any problems. Oculus has and will check on the purchaser information first and will deny help if any information is found that the item was resold.
Reselling in Europe is not forbidden though and with the proper receipt, received from the reseller, they still have the rigtht for warranty. I do agree that it is bad though and oculus should stop them before they gain there rifts.
Also..its stupid for buying these from Ebay when you can get them cheaper from the manufacturer.