The alcoholic drink order..

I admit, I was multi tasking while watching so I may have missed this. My question is: Why didn't the stewardess bring Marks his alcoholic drink, and give him (water?) instead?

Is this part of his ruse to cover his identity to other passengers? What if the stewardess didn't know him like she did in this movie? Are stewardess and pilot staff aware of air marshals?

Did he really want a drink but the stewardess refused to do that for him, knowing his job, and gave him water instead?