Excellent advice and I agree that your pup is not yet food agressive. You are doing everything you can to make sure he/she will become food aggressive, I'm afraid.
As pack leader it is your job to take the best bits of every meal BEFORE the rest of the pack are allowed anywhere near it. The pack leader only allows access to the food when he has finished with it and NEVER returns to take more after the pack are eating. Once you give your dog it's meal you are telling it that this food belongs to the dog and nobody else and it is well within it's rights to defend that food. From the dog's point of view you are behaving very strangely, unfairly and threateningly. If a canine pack leader behaved this way it would be seen as a bully and the pack would lose confidence and became fearful.

Of course, this is not your intention, and to human minds it seems a really good way of showing our dogs that they can trust us with their food as we will not steal it. Your dog will become more relaxed about food if left alone to eat for five to ten minutes undisturbed. You can teach your dog to take food nicely from you by using some of it's meal as treats during training sessions.