I saw someone watching this, so I googled and watched, I wanted to be really dangerous. A sissor kick is that really the best they have? I have tried this on unsuspecting people and the best I got was a bruised coxics.
Then I tried it on the fast lane of the M6 and it all fell into place.....
You have to remember that Judo and BJJ (or Brazilian Judo as it should more accurately be called) are sports.
Kano took all of the dangerous techniques out of Ju-Jitsu so that it could be practised at full speed (and taught to children in school) without injuring your opponent. So the throws/takedowns are not designed to injure people, they are designed to put them on their back as that is how you score points in a Judo competition.
So it depends on the persons definition of "dangerous". Dangerous as it puts them in a vulnerable position in relation to having an ippon scored against you, or dangerous in terms of inflicting physical damage.
It is about context isn't it? Most throws are dangerous in the context of your opponent may pull you over with him or you may over-balance. This a kind of sacrifice throw and is interesting to practice in the context of game-play but would in reality only be attempted in desperation. Personally I like to practice things now and again that are not strictly, pragmatically useful, simply because they are fun! I take your point however; it is stretching things to call this throw in particular in any way dangerous.