Turbo boost is a dynamic setting, in that the system will boost things if the kit is up to it. However, it's designed to conserve power (which reduces heat too), so if you're not using anything to take advantage of the added boost, it's just going to waste anyway.
No reason why it shouldn't be safe. The throttling will still be applied if the CPU gets too hot. I suppose if you have a particularly bad cooling / airflow situation, enabling turbo boost could heat things up to trigger throttling. Never tried to test that tbh.