Space X and other New Space companies proved that one can use commercial grade components up to Low Earth Orbit (LEO), dealing with much lower total dose and single effects radiation.
The risk of using those in higher orbits and in deep space increases exponentially...
There's a reason NASA uses space grade components for deeper space missions, and no commercial plastic components...
Space X would need to use two or three orders of magnitude costlier components, and more qualification testing, before even thinking of sending a single probe to Mars...
Elon probably thought a new NASA management would have borne the cost of that for Space X...