Yeah, in most cars, the redline is a caution. Most manufacturers purposely set it low. So, no, the engine isn't going to grenade if you go over it.
I hate those freakin' pushbutton starters, and the things are showing up everywhere! As you said, there is no simple turning the key to kill the engine in an emergency. Not to mention the special key fobs are usually terribly expensive should you lose or break one. I hate the things. What exactly is wrong with keys? I'm also glad I have a manual transmission. Try stopping me from shift that one into neutral!
I don't mean to get off on a rant here, but...I hate a lot of this useless stuff going into modern cars. It's one thing I love about my car. There's no remote key fob or push button starter. No adaptive cruise control or lane departure system. No huge, distracting screen in the middle of the dash. (Playing movies, no less.) How about people learn to drive? Stop yapping on the phone, putting on makeup, shaving, stuffing your face, or reading the newspaper and DRIVE! Pay attention to your surroundings. It's not that hard.