Meh, they've tested Newton's laws numerous times. If everybody knew them, both intellectually and in their bones, they wouldn't have the myths to test, but alas, I don't think you can claim with a straight face that we live in a society with universal knowledge and deep understanding of Newton's laws.
... and if you think you do, spend some time on the much-referenced "fan site".
And furthermore, there is nothing unscientific or wrong about testing our most well-tested theories. The entire point of science is that even then, the theories will still work, not that you should never test them again.
I'd also further observe that for all the drama happening here, those swinging gun sequences aren't that unsafe. It may look unsafe but the actual set of things that can plausibly go wrong was less than your intuition may be claiming. It's not like there was a way they were going to shoot themselves with a particularly higher probability than usual. (And remember that if you start constructing far-out implausible scenarios under which that might happen you must be willing to worry about equally improbably things all the time; one rapidly gets to the point where things like simply driving to work must be considered too unsafe to do if one starts spending too much improbability on the constructed scenario.)