I am glad you brought this up because there is a difference in being paid in Bitcoin and being paid in dollars and then having them converted to Bitcoin. If his salary is quoted in dollars then the actual amount of Bitcoin that he receives will be dependent on the exchange rate and therefore will fluctuate.

If his salary were to be quoted in Bitcoin such as you will receive 3000 BTC per year then he would get 3000 BTC regardless of the exchange rate. There is a tremendous difference and people don't make that distinction.