Abortion has nothing to do with the Las Vegas shooter.
For one thing, the shooter was born, or otherwise he wouldn't have been in that hotel room on the 32nd floor.
Morality and ethics still exist in the world.
Despite your overly simplistic thinking, the vast majority of people don't think "Gee abortion is legal, there are no rules, human life has no value, so I could shoot someone on 5th Avenue in broad daylight and no one would notice!"