That corruption exists on both sides - this is understood by pretty much everyone who isn't wildly partisan. That there is both legal (meaning that it does break specific laws but is instead privilege accessible by those in circles of power) and illegal corruption, likewise.
In the case of Hunter Biden, he is just reaping the benefits of being close to power. This isn't illegal - ex-presidents go on the talk circuit to tutor people in how to handle specific situations or to discuss events they have encountered. One would think that Hunter Biden would have received a masterclass in power politics through his father having been VP for 8 years. Her certainly would have met a lot of people over the years who could help him in the real world. This is not illegal, this is just one of the privileges of privilege.
Privilege is human nature. There is no mystery club - you are just either inside the tent or outside the tent. This does not mean we should not break it down, or tear it up, but it is also not illegal to hang out with people who are like you and who get you.
The problem with Greenwald's pieces are that he conflates this with obvious, illegal corruption. He claims it to be illegal - which is is not - and conflates it with actual corruption... but only on one side of politics. He seems to see himself as a maverick, a lone-wolf, but then whines that no one is there to support him, and all the legitimate papers decry or ignore him.
Greenwald is either unwell (and who isn't these days) or is trying to wedge himself into the role of the "reasonable" right-wing partisan. If it is the first, I hope he recovers, if the second, I hope he goes down in flames. The world needs fewer partisans.