So, why has it got out of hand to the point of what sounds like illegal activity that the SJW do? Is it becuase SJW is a leftist movement (not saying the other way around is better) so people are not as critical of them?
Sort of. It would be more accurate to say that people in certain arenas completely refuse to criticize them or hold them to any standards of behavior, most importantly on many college campuses where these people are living as independent adults for the first time in their lives.
What happened at DePaul with Milo Yiannopoulos is a perfect example. Whatever you think of Milo's opinions, he was a paid speaker there. Furthermore, the school unfairly screwed over the people who wanted him to speak by forcing them to PAY OUT OF POCKET FOR EXTRA SECURITY before he was permitted to come, something they had never done to a left wing speaker.
Then he comes to speak and a bunch of Black Lives Matter activists rush the stage, seize the microphone, nearly punch him in the face, and refuse to let him speak. They successfully shut down the event because the faculty ordered security, SECURITY THAT THE PEOPLE WHO HAD HOSTED THE EVENT PAID FOR OUT OF THEIR OWN POCKETS, not to intervene.
Think about that. Even if you completely disagree with Milo's politics, think about that. Imagine if a group of skinheads came to a left wing event on a college campus, rushed the stage, grabbed the microphone, physically threatened the speakers, and the faculty of the campus ordered security not to protect the speaker or escort them out. Imagine that people were forced to hire their own security every time they wanted a left wing speaker to host an event on their campus, but not the other way around, and then the campus administrators STILL actively work to undermine their event. Liberals would be up in arms about living in a fascist state. Well that's reality for many conservatives and libertarians on many campuses in the US and Western Europe.
By and large, people who are part of the so-called "regressive left" are spoiled brats who are used to throwing tantrums and getting rewarded. They act like they're oppressed, but in the circles they run in, they are actually constantly treated with kid gloves and benefit from unfair double standards. They get hostile to people asking questions because they're not used to their ideology being questioned or challenged. They harass and threaten because experience has taught them that they won't suffer any real consequences for it, and that most of the time it will work.