This isn't just about legalizing assisted suicide, this is about removing the stigma behind it. Legalizing goes a long way in doing that.
There is such a huge amount of shame involved with the topic of suicide. You're seen as a failure or a quitter or a reject. So much so, that people will put themselves into untenable situations with cops (or other armed people) just so they can get shot. In their disassociated mind, if it wasn't done by their hands, then they don't have the guilt or shame of the act.
For some people, by killing others (loved ones, strangers, places where emotional trauma happened) it justifies their suicide and removes the shame from it. When you have disassociated so much that ending your life makes sense, then you have zero chance of valuing the life of others.
I don't mind if people don't want to believe this. But as the years roll on, you'll keep seeing the correlation between suicide rates and mass shootings and start to understand what is going on here.
fwiw the shooter here was arrested and is alive, like Dylann Roof and the Aurora, Colorado shooter.
Many people fail at "murder by cop" or kill loved ones and then can't bring themselves to kill themselves.
You really think those people went into those situations thinking they were going to get out alive?