Re: What to do ?
I dont know about others but if such a problem would arise in our dojo I as one of the "seniors" would toss the person out personaly. I am responsible for the safety of my fellow aikidoka as well. I will not allow anyone to threaten or intimidate my training partners and as "senior" I will carry the burden of responsibility.
If you wanna train in our dojo you follow the rules. If you cannt follow the rules or arent willing to follow the rules then you are free to leave (either voluntarily or assisted).