It is a totally false argument. The fact that his first statement is true doesn’t mean the whole argument is. It’s a simple logic problem- if “a”, then “b”.
So, modern cars are safer than our old muscle cars. That’s true. That’s “a”. So then the rest of the argument. If modern cars are safer than our old muscle cars, then “b” -paying attention to safety features on our old muscle cars is like “we are straining out the gnats and swallowing the camels on this one”.
But “b” is false, and it doesn’t follow from “a”. We can still make our old cars more unsafe. We can also make them safer.
So no, just because modern cars are safer doesn’t mean we shouldn’t care about making them even less safe. So the argument is false, even though his first statement is true. Simple logic bud.