Most of the sets I own have a hole in them, so I think for the scenario that the average person does actually have a torx set, the chance is pretty high that it's also one that they can use on those "security" torx screws. So I don't see them that much more secure than regular torx.
The only reason I could think of is that you also can use a normal screwdriver to unscrew a torx, which is harder to do with that extra pin. But it can still be done^^
If you're determined enough you can jam a slot screwdriver in a torx and turn it, the security bit makes it so that you have to be REALLY determined when you jam the slot screwdriver in