While that article isn't the worst I've seen from Cesar Milan, it still heavily relies on the debunked idea that dogs are constantly challenging us for 'dominance' in the home and living with a dog means constantly having to find ways to make your relationship a fight you can 'win' or do silly things to prove you're an 'alpha'. Dogs do not have any kind of hierarchical pack structure among each other, let alone in their relationships with humans - wolves
don't have a hierarchical pack structure, and they're what 'dominance theory' was originally based on, even though they're hugely behaviorally different than domestic dogs.
More specifically, in this case, eating before your dog will not do any harm, but it also won't do any good, either. It's completely irrelevant to dog training. All it does is reinforce the idea in the human that their relationship with their dog should be a constant battle, which is pretty sad in my opinion.
Backing away from the food bowl if your dog growls isn't inherently bad because you let the dog 'win'. It's showing the dog that you see their signals and you're respecting them, so they don't feel like next time they have to tell you off even more (possibly with their teeth) because you won't listen to a less intense warning. This doesn't mean you should be testing your dog's limits all the time by making them growl and then backing off, but if you accidentally push them to that point, often backing off is absolutely the best solution.
Here's what I'd suggest in the short term: feed your dog in a crate or pen so that he has a barrier between you and the food. Many dogs anxious about their food find this a little more comfortable, because no one can get into them easily to 'steal' anything, and it's safer for you because there's no bite risk if the dog does get upset enough to go that far (especially if you have young kids or visitors who don't know to be careful around him). Have a handful of high-value treats (more exciting than his food), and anytime you go by him (not close enough that he starts growling), toss one into the crate/pen for him. Don't linger, just toss one over and go about your business. This will help teach him that you being around when he's eating is a good thing because tasty goodies show up.
Outside of mealtimes, you can practice trading games - googling 'trading games dogs' or 'trading up dogs' gets some useful articles and videos for more details - where you 'trade' him less exciting toys or chews for more exciting toys or chews. This teaches him that giving his nice things to you is awesome, because you give him nicer things! This makes it easier to 'trade' him for things he shouldn't have (the mail, shoes, plastic packaging, etc.) without him guarding, and makes him less stressed overall with you being around his treasured items.
I second the recommendations for Mine! by Jean Donaldson, but for the general 'what do I train'? Definitely watch this video!
Lots of awesome, easy foundation behaviors for puppies - the thing I personally tend to teach first is their name, because there's nothing the pup can get wrong. You just say their name, then give them a treat. Do it a few times in a row, a few times a day, and boom, your dog thinks their name is awesome and starts looking at you when you say it! Great way to get started in diverting their attention from 'bad' behaviors, improving focus, and the foundation for a nice recall. Good luck!