anyone who considers eating in flight to be 'poor airmanship' is living in a dreamworld.
I have eaten while flying...from cold Army C-Rations to proper meals from first class catering during VIP events.
There is one particular Bristow S-58T crewman, later he went on to SAR duties, that if he knew how many smoked Salmon sandwiches I ordered up (he would only eat boiled ham sarnies and would invariably hand up his Salmon feasts to me, he would beat me to death.
One has to be aware of choking hazards during single pilot ops....or perhaps spoilage concerns if the food items are saved for the. next ground stop if Ambient Temps are high.
But....as that Eacott fellow says....in a most polite way....if you really think eating is bad form....you have lived a very cloistered life.