By "the only one available" do you mean there are no other options that would be possible to implement in the future? Or do you mean it's the only option available at this time.

It's the only option available at this time.

If someone flags my post when it shouldn't have been flagged, and my only option is to retaliate by falsely-flagging their post, I'm not going to flag their post out of fear of retaliation.

This is when you can enlist the help of a whale or two or three. There are bots that could also help until the flagging abuser gets the point. I'm not saying it's the best option, but currently it is the best option if they will not remove the flags.