Totally false argument.
It’s true, these cars are nowhere near as safe as a modern car. So we’re all assuming some risk we wouldn’t be if we drove new cars.
But that doesn’t mean we should overlook simple safety improvements, or make unsafe modifications. If the seat rips off the floor you’re going to be in worse shape than if it doesn’t, it’s that simple.
Just because these cars are less safe than a modern car doesn’t mean we should ignore safety entirely. If anything, we should focus MORE on the safety we can control or improve.