I'd say it's hogwash.
Number portability is just that, shouldn't matter from where to where.
The only limit to be aware of is fixed landlines can't have numbers that don't belong to the region, so if you are in say Montreal, you can't bring your Toronto phone number to a fixed landline. That said, there's nothing stopping you from using a VOIP provider instead. I moved out of the city but thanks to Vonage I still have my city number.