The Q2 mechanical diff isn't primarily a safety aid per-se, its designed to allow you get *more* speed out of the car by optimizing the total available traction.
It doesn't increase grip in any way, just mechanical traction (power transmitted to the road).
You could argue that it gives you more control over traction so helps safety a little in that sense, but more traction equals more speed.
Of course reducing understeer under heavy throttle could of course be construed as helping safety in a few situations, but this is probably not applicable to most accident avoidance scenarios.
Something like ESP is a safety aid since it can detect when things go haywire especially on the road and then intervenes
But the mechanical Q2 works ALL the time, continously transferring torque in a close to optimal fashion so you power gets to the most useful wheel to go fast or simply avoid wheel slip in wet conditions.
This is useful whether pulling off smoothly at the lights on a wet day, or haring around a track.
On a windy road you can feel the benefits without being a complete hooligan, you can just smoothly apply the power earlier out of corners than without a Q2 diff.
I suppose the intriguing thing about the Q2 limited slip differential is that in some ways you kinda hope you never have to rely upon it bearing in mind it's a safety measure after all.