You are right in that if American society was functioning like a normal rational society, we would acknowledge that the president's son did something wrong, and laud that he is being held to account for his wrong actions.

But, and this is just my guess of course, the right wing groups in America are going to see this as vindication for investigating every Biden and ignoring any Trump or Trump family illicit activities. And if there were evidence of other wrong doing by the Bidens, then by all means they should be investigated.

But this will all be used to either redirect attention away from Trump and his various court dates and activities, or be used to rationalize (more than what is already happening) all of it. Either way the end goal would be to fire up the right wing base, and use it as talking points, whataboutism, and redirection from Trump and his family.

Multiple things can be happening and be investigated at once. But the right wing media and voting base don't want to acknowledge that.