How do we stop this from happening?
I do not think this is possible as aikido has spread so quickly and there are so many different organizations and splintered groups. I know of an aikido sensei who also practices/teaches another martial art. This art is not very wide spread and is as far as I can find located in the state he lives, Hawaii. When a school opens and they claim to be teaching this other style, since it is very closely monitored teachers of this style know one another pretty well, so if the individual is not legit they are merely confronted and told not to advertise as such or face certain consequences. Meaning a serious spanking as I interpretted. So in short unless we go back to the day of dojo storming frauds will continue to pop up.