Answer:
he was discriminated solely based on his sexual orientation.
Step-by-step explanation:
The Title VII of the Civil Rights Act of 1964 stated that all employers in united states are prohibited to discriminate their employees based on race, religion, gender, national origin, and sexual orientation.
You do not need to be married for your sexual orientation to be acknowledged by the The Title VII of the Civil Rights Act of 1964 . You just need to proof that any of the factors above are the reason why you're discriminated against.
In Qiang case, he could tried to find witness by talking to other employees or find a recorded email/messages that indicates his boss mistreatment toward him. If there are enough employees who came out as witnesses, he could build a strong enough case to gain support in the court.