You can learn morality and ethics doing anything you want if that is what you get out of it.
I was talking to some guys who train in jiujitsu with me today about this. They don't feel they have learned ethics in any martial art training. What they did learn was humility and confidence (in that order).
I agree. When I first started I had false confidence from my previous martial art training. I was humbled and force to deal with my delusions. Later, and I got better I gained real confidence. I know where I stand in terms I can quantify. This has lead to a reduction in aggression, a desire to help others succeed, and inward and outward happiness. I'm less introverted and able to assert myself more directly in public. It has helped my job, my teaching, and my personal life. The best part, my teacher just taught me how to choke, pin, and armbar people. The rest just came from that.
Now as a part time teacher I also do not try to push my values on my students or even mention them. Instead I focus on building their abilities, confident that they non-physical things they gain will be their own.