I also don't think you clearly know the difference between a "Please put me down now!" bite and an "I wanna kill you!" bite. If it were an "I wanna kill you bite", the dog wouldn't have stopped. It would have snarled and kept biting you even when you stopped the offensive action. If it were an "This doesn't feel right, put me down!" bite, the dog would have given a quick snip and immediately stopped once you stopped the offensive action. Furthermore, the dog would have shied away from you whereas an attacking dog would stand ground or perhaps even bolt forward.

14 weeks is incredibly young. For neglected and possibly abused dogs, it could perhaps have been 14 weeks of hell from human tormentors. These dogs obviously associated humans with negativity, and I would have expected you to know that...Even if you don't think you can take them on, you could at least keep them for the time being until you find another Great Dane foster. Many people have rehabilitated dogs previously used for dog fighting and dog bait. Rehabilitating a 14 week old puppy is much easier. Please give these dogs a chance!

Edit: I was right. Sub backed away when you try to touch him. He's terrified! He's not trying to attack you. He's scared and needs some serious TLC from a conscientious owner. Please be the one for him.