At one point the boyfriend reveals the pistol, but does not fire upon the swimmer. This is called brandishing and is considered a crime in and of itself. The swimmer was understandably afraid for his life and called the cops.

Even as someone who wants brandishing laws loosened, this is 100% a crime that could go way worse than just "brandishing", in some states it's considered aggravated assault and you're looking at 5-10 years in prison for flashing a gun.

The swimmer filed a civil suit against the female officer for excessive force, and the court threw it out because he "resisted arrest" despite complying with basically every order.

That doesn't match what the news said. The news said that the case was dismissed because she had probable cause to make the arrest because he resisted.

... which still doesn't make sense, not only because I didn't see resistance besides backing up, but I don't see how a question on probable cause is related to the justification of pointing a lethal weapon at someone. Probable cause is simply to make the arrest. That has no bearing on the use of disproportionate force.