What should be residential status?

Non Resident...

Sir, is it because he left for employment? 

Yes, otherwise second condition for RI would have got satisfied!!

182 Days in India one of the  condition  for Resident Indian 

Ok, now I clearly understand this. Thanks sir.

When left for Job, second condition of residential status gets modified to 182 days.

So, his residential status for FY 2018-19, is Non resident.

As for NRI, any income earned outside India is not taxable in India.

Generally not questioned, unless any under reporting or misreporting.