True that turbo timers are for turbo cars and are primarily used to cool down oil that is circulating inside a turbine. Its not so much to cool down the engine in general as our radiator is pretty good enough to cool down the engine after a few hours of heavy driving. Come on, cars are design to take quite a bit of a thrashing, and thats the reason why our cars are rev limited anyways.
So is there any reason at all for NA cars to use turbo timer, absolutely no as no matter how hard your car is driven, your engine radiator does a pretty good job at cooling down the parts after the engine is switched off. If no, then you probably will see a notice in your car manual that says after 3 or so hours of driving, you must leave your car idling for 2 minutes before shutting down. So don't worry about cooling your NA cars.
And whatever Apexi is marketing is their problem. Quite obviously its part of marketing strategy, that to put For NA and turbo cars. They very well know this is not necessary but installing one will not do any harm at all.
So i'd say, if you like it, just install it for the sake of it and to look cool. But there's no benefit at all.