Scorpios are indeed control freaks, but maybe not in the way you expect them to be or in the way, most stereotypes paint them.
The reason why Scorpios end up being second among the zodiac signs that are control freaks is that when it comes to people they love, they are going to go above and beyond to make sure they are safe and sound.
In reality, Scorpios are protective and possessive, which in turn can end up being controlling since they want the best for you according to their own views. They internalize this need to take care of people and make it their responsibility to ensure that their loved ones are safe and sound, which in turn can be seen as controlling by the people around them.
Sometimes it is not that the zodiac signs that are control freaks are truly as controlling as we perceive them, but their innate drive towards certain goals makes them act in such ways and strive to have control over certain situations.