Their definition of "constructor" is as something that will perform a task reliably (whose meaning they define as including repeatably) for any choice of input

Their definition of "constructor" is as something that will perform a task reliably (whose meaning they define as including repeatably) for any choice of input with the specified attribute. If you can't come up with some reliable repeatable way of turning any cooked egg into a raw egg, then you don't have the thing they call a "constructor" for turning cooked eggs into raw eggs.