Well, if one is using agar, some form of heating is necessary. And I felt that stovetop boiling would take long enough that too much of the alcohol would evaporate. This one, two minutes is enough to set the egg and to heat the liquid to activate the agar, but not long enough to burn off the booze.

Egg whites, and eggs in general, are a traditional ingredient in many classic cocktails. Nogs, as a class, include eggs and cream or milk; flips contain eggs, fizzes contain egg whites. A gin fizz is a gin drink shaken with egg white. And other stuff.