Just because it turned out the driver was sober does NOT make investigating a weaving car a "hoax". Don is just a careless driver. The difference between a "fan" and "agent" is often hard to discern without careful investigation.
And just because clear "collusion" wasn't found, obstructing the investigation is still not warranted. Don clearly tried to influence the investigation itself, and Mueller pretty much found him guilty of obstruction, but said he's not recommending charges (at the time) because a sitting President is likely legally protected from such during their tenure (based on legal analysis by another agency). Interfering with an investigation is pretty dumb, actually: if you are innocent, there's little reason to attempt to thwart the investigation. Don is ornery out of habit and paranoia.
