On the other hand, it used to be very common for malware on Windows to email itself to all your contacts using your real email client. It's probably reasonable for an OS to add a little friction to the process in the modern era, though it probably shouldn't lie and claim the binary is damaged when that's not the problem.
chmod to dequarantine doesn't sound like "a little friction" to me.
On your point about security, this kind of aggressivity from the platform owner tend to backfire.
The user was already convinced to open that mail, download that file, and try to run it. Pushing the process to the terminal just means your clueless users now run the provided incantations in the shell instead, and the attack vector now becomes huge (the initial program doesn't even need to be malware)
I agree having to go to the command line is too much friction. Just clicking `overdue-invoice.doc.pif` is too little. About right is somewhere between a prompt and setting the file executable in the GUI.
