There is no "misapplication of the rules for neutral wires" since neutral and ground are two different wires with two VERY different purposes, regardless of the fact that they connect to the same place in the main panel.
A main panel does not typically have separate neutral and ground bars, so if yours are separate then someone either needlessly put them on separate bars, or they added a dedicated ground bar. A photo of your panel would clarify this.
Either way, either of your choices is FINE and a safe and legal solution. There is NO problem with putting two, or even sometimes three, ground of the same size into one hole in a ground/neutral bar. As you know, the same is NOT true for neutrals.
A third option as War stated is to add a new ground bar to the back of the panel. Add-on bars screwed to the back of a panel box are to used for grounds ONLY.