I'm not saying, Psycho Mages run rampant on the streets with lesbian vampire ninja elves. Just that the percentage of both is significantly higher _running the shadows_ than them occuring in the world that occasionally sees the light.
I liked the fish metaphor made earlier.
When you look down from your boat, on the top of the water you see the big swarms of small fish. They are tasty and look shiny as they move through the ocean in giant quantities. Those are the general populace, obviously.
Below them, there are the sharks. Sometimes they eat the small fish (even if Finding Nemo tries to teach you something else

), but mostly the small fish don't even see those big maws.
And below the sharks .. in the dark ... there are the leviathans, that even the sharks hide from.
This is more of a stream of consciousness right now and I hope, I get my point across.
Yes, there are psycho mages. The general populace fears and shudders when you tell those stories at a campfire, but if you get to a 100 years of age, you won't ever meet one.
If you are living in the shadows though, the story might be different. You'll meet mages during your life and criminal career, and one or two of them might be seriously whacked out and dissect puppies in their basements each sunday. On the other hand, if you're crossing paths with these people, you might be a samurai with a reflexbooster and perfectably capable of killing the mage before his spell goes off.
I asked those question because I've seen issues like the ones you're describing before.
In short, the probability of such behaviour rises with lower average age and, believe it or not, when the players have mostly played 'hero' type RPGs before.
SR is, in comparison to, let's say D&D and its derivates rather sandbox-y (yes, that's a word now, if it wasn't already) and you don't actually play a hero that gets away with most of the stuff he does, because well, ... he's a hero. Not only a hero, a protagonist even!
You've played a nice mage in Fhaerun (or whatever that world is called) before and crawled your dungeons and found the treasure in a usually rather organized way. There is no moral question, because dragons are colour coded for your convenience. I'm exaggerating, of course, but I hope the point gets across.
Now you're confronted with playing a criminal with possibly superhuman capabilities. Suddenly you have the the question of how said criminal interacts with those around him that are significantly weaker than him, and there's no real mechanic in place to punish you for bad behaviour, apart from in-game laws and consequences.
It's just natural to experiment a bit to get your bearings, and by doing this, a typical group will encounter different ways of approaching these moral questions and sometimes there will be a need to discuss just how deep and dark you want to take your game.
I've heard a comparison once between CP2020 and SR, where it was said that the good fairy gets raped and killed, but the question really is: Are you and your group comfortable with topics like these? You don't really get an answer if you don't discuss the topic. Offplay, that is, not just deciding one-sidedly and using the inplay hammer and _telling_. (Not that I'm insinuating that you're doing this)
Coming from you, Tiberius, and your fellow player, these are at least 50% of the people sitting at your table that do not want to deal with the mindrape topic as a regular occurrence. Judging from this, I'd say that there is a need for putting the subject on the table