Declining to prosecute someone for a crime is different than going along with it.
If Biden were to declare by executive order "these 26 people are now Supreme Court Justices" that doesn't make it true if the Courts and Congress don't agree to go along with the illegal order.
It actually applies to Trump too. He stole classified documents, Judge Canon dismissed the case, but the national archives aren't going to be giving the recovered documents back to him. He illegally tried to overturn the 2020 election results. The case may be dead now that he has immunity, but that doesn't mean he's allowed to overturn the election and that he's President now.