If I delete a file on my computer without doing a secure delete, I know that the data is still on the disk and can still be recovered. However, I also know that in normal operation of the computer, that data will never show up again. There are no circumstances where I can create a new file and have it get filled out with the contents of the deleted file. There are certainly no circumstances where another user on my computer can do that and get my data.

I would have every expectation that this scrub option works the same way. That it defends against specialized recovery efforts, not random people making new VMs. DO's documentation says nothing to indicate otherwise.