• Whether I am employed or not

I want to ask this question on behalf of my friend.

He belongs to OBC category. 
He went to USA in August, last year. Before that, he was unemployed and hence he was non-creamylayer OBC
He went to USA on F-1 (non-immigrant) Visa which is valid for 5 years.
He went there as a 'full time graduate student' in an University. Also, he is appointed there as Teaching Assistant (TA), which is the ESSENTIAL PART of his curricula. University has waived his tuition fee and provide him the STIPEND of $2000 per month for his 20 hours a week duty as TA  (he also pays taxes on this amount). 

These summers, he came to India to appear in a written exam held by UPSC for a group A, gazetted officer post.  Now he has qualified the exam and he has been called for a interview. UPSC is asking a few questions e.g. whether he is currently employed or not, if yes what is his SALARY, Whether he is OBC Creamy layer or non-creamy layer etc.

As a result, now he is confused on a few points.

Whether his STIPEND should be considered same as SALARY according to Indian Law. 
Whether he should be considered as an employee or not (as being Teaching Assistant is the part of his curricula and he is 'full time graduate STUDENT').
 If not, can he logically and legally be considered as Non-Creamy layer OBC.