Sace, labs are very prone to problems of inadequate bite inhibition especially when they are separated from mom and littermates at 6-7 weeks. What happens is for the rest of their life they are more likely to mouth hands in greeting, playfully nip ankles, hands, faces, or even actually bite when the situation doesn't warrant it. Nothing you can do to fix what someone else messed up on years ago, you have to approach it from a completely different angle.
Teach that the proper way to greet a person is sitting. Hopefully your friends will listen when you ask them not to encourage him jumping up. A scratch on a child's face, or pushing them over is not acceptable, and dogs are not that good at distinguishing, oh it's okay to behave crazily with these old guys but not with fun-looking little ones. You and your friends can give praise, petting, treats, attention, when he's calm and sitting. Jumping up, sometimes you can discourage by ignoring him until he's behaving well, sometimes you have to be more forceful such as a very dominant behaviour of walking directly towards and into the dog until he backs off. It will take work, but old dogs can be taught new tricks.
Another thing that can help with labs is getting them to carry a toy around - if their mouth is full of a toy, no room to fit a face too. As a retriever they like the feel of something in their mouth, so get your guy to enjoy toys instead of bodyparts. Again, use encouragement when he's doing it right. Make sure there's always something acceptable available for him to pick up, including by the door, and you can even hand him something to hold.
It is also possible that your dad bending over Tobi caused a fear/dominance reaction due to something that happened in the past. Keep an eye on it just in case, and when these things happen take quick note of whether he was displaying any other signs of fear or aggression at the time. You can still correct the issue, bit more work. For now, work on teaching him better manners, it may well be as simple as that.