I'm not sure if this is the case specifically for avocados, but many of the limits Dr. A specifies during Induction are because it's easy to overindulge in these items, and he crafted induction to make almost anyone succeed.

For instance, Nuts. Nuts are great. However, if you're still fighting cravings, you may eat TONS of nuts. Once you're solidly in ketosis, your appetite will likely be suppressed to the point when you can control your portions of nuts.

In ketosis, it's tricky to gain weight, but if you consume too many calories, especially of dietary fat, you'll make it so that your body does not need to burn your body fat for fuel, defeating the purpose of the diet.