More hogwash - an automatic shoot down is not guaranteed with 7500.
I have no idea whether it is or not guaranteed - I am not "in the know".
But given that the exact policy is likely to be "secret" I have no way of knowing, so I think I'd just not take the risk...
On most big jets the squawk is buried deep in the FMS menus and won't be obviously apparent unless you know where to look.
Perhaps on some, but certainly not on all.