If you have your own phone to activate you can keep your unlimited. You have to buy a phone outright to keep your unlimited and telling you to lie about a phone is not good advice. If your phone is a subsidized device, they will know it and you won't be able to keep your unlimited.
I was not happy when the plans were changed but when I realized the amount of data I really use, making the switch will save me money. Also you can use wifi free. I wouldn't try to fool Verizon because you won't get away with it. And the rep who suggested this.....I used to be a manager with Verizon.......I would be careful what you say and suggest to customers. A good sales rep will be helpful and honest to their customers and not give suggestions that may lead to being dishonest. It will backfire and then the customer will be really upset. I saw a lot of things misrepresented and it isn't right. No wonder customers get an attitude!