Amusement Parks tend to have food to feed hundreds of people visiting the park in a day so there could still be some left if said survivor has made it to save some of the food that has not gone bad.
The Amusement Park rides might provide entertainment however. (read the section below for more details.)
The Amusement park is HUGE so fortifying a section can be very time and resource consuming.
The rides can provide entertainment however most to all tend to have bright lights that can be seen for quite a distance during the night, and tend to be very noisy. To put it simple if you wish to restore the power to the Amusement Park without thinking or checking for zombies and bandits in the surrounding area turning the power back on in the Park would basically be a beacon for zombies and bandits which allows them to locate you.
It would take a small army to secure a simple section of the Amusement Park.