Re: dojo head bans students from training with another teacher (ex student)
If I had been told I could not go train at a friends school I to would be asking why, getting told its personal is simply not a good enough answer IMHO. I would be a bit suspicious to the reasoning of being told no and would wonder how much of it is to do with egos and how much of it is down to the quality of the teaching and training.
In the end though I think that I would put my friend before the club and go along to his class. Surely it is better to practice at any opportunity you get to help improve your techniques etc rather than to be led astray by what appears to me, and feel free to correct me if I am wrong, by politics.
I am wondering also, just out of me being a nosy parker why is it etiquette to ask if you can go along to the friends class to train. It could be me not getting some sort of tradition of aikido or your particular branch but that to would have alarm bells ringing rather loudly.