The problem is a lot of the criticisms of these corporations are entirely correct. Not one of them produces a quality machine worthy of being used in an election. They may not have themselves stolen an election but the sheer number of defects in these devices calls into question the legitimacy of any close election, even if in the case of Trump, his accusations are entirely self-serving and mostly invented. He made it clear in the months leading up to the election that he was just going to scream fraud no matter what if he lost. So a lot of the criticisms of their product are substantially true. They'd have to show they deliberately lied about the others, or that the others damaged their reputation even more than the lack of quality of their own scandalously bad products. I.e. even if they didn't actually steal the election, their products are so shitty it is entirely reasonable for people to suspect that.