While there is yoga in some of what the SBBS teaches, like understanding the power of Shabad, or relationship of Guru, Sikh religion is not about yoga.

Harbhajan Singh Yogi (Yogi Bhajan) was a kundalini yoga master. So, that is what he taught. He was also a Sikh, so that also is what he taught. Sikhism taught to American students by Yogi Bhajan is a yoga path. But if you were to go to an Indian Gurudwara, they would not be teaching yoga there, only Sikhism. I do think he has taught some very good things though.