Not correct. Only the driver's seat belt need buckling up before you can accelerate to release the Park Brake. Front seat passenger can take own sweet time to buckle up
In fact, this is one of the features that attracted me to the CX-5. You know for some drivers (esp new drivers), when they are parked or stopped on a slope, and if it is manual Hand Brake, there would often be some roll-back. Even for automatic transmission. So, this e-Park Brake system kinda' resolves this issue. All you need to do when you stop on a steep slope for a moment (maybe a traffic jam or red lights), is to first step on Foot Brake, use your little finger to activate the e-Park Brake, and wait. If you are safety conscious, your foot can remain on the foot brake while in wait.
Once your journey resumes, all you need to do is to release your foot on the Foot Brake and step on the accelerator gently, and move off gradually. There's no need to de-activate the e-Park Brake! But do remember to keep buckled up or this would not work.
Cheers!