Justice didn't have a case.

I think that quite a stretch. It completely ignores all the US Intelligence agencies' findings. Those were not opinions. Those were real analyses of internet traffic, real evidence of phone call patterns, etc. It's a lot more plausible to think the cases were not prosecuted because they threatened Trump's fantasies about winning the election without Russian help. Especially since the Justice Department has repeatedly sided with Trump's agenda over respect for the law.