That is not a realistic test, as any space engineer could’ve told them. First of all that’s on the very low end for a cosmic ray, an order of magnitude below the average energy. But the average energy doesn’t matter because there is a very wide distribution and the much more intensive cosmic rays do far more damage. It was also not a fully integrated test with a spacecraft, which matters because a high energy cosmic ray, striking other parts of the spacecraft, generates a shower of secondary particles that do most of the damage of a cosmic ray strike.