Purported white-hat hackers. The implication is that these people are presumably describing themselves as such, but it may not actually be true.
Where I live it's only theft if there is an intention to unlawfully take ownership of the good. As an example, forgetting to pay in a supermarket lies exactly on that boundary. Take a cart or hide a product and you won't get away. Try to pay, payment fails and you don't notice, walk away and get apprehended and you might convince the judge that you had no intention to unlawfully take ownership.
Kind of in-between I'd say. You find a wallet, on a bench, next to sleeping person, and you see lots of other people eying the wallet to take for themselves. You take the wallet to prevent others from taking it essentially.
Not saying these people for sure are whitehats/grayhats, who knows until the funds are returned, but that's basically how grayhatters see themselves.