????? ?????? allows a ????? to benefit from work done for him by a ??? on ???, IF the ????? did not specifically require that the work be done on ???. Once the ????? indicates that the work must be done on ???, this ???? is out the window. Obviously, this includes a job which can only be done on ???.
The concept of ????? ?????? is that the ??? chooses to do the work on ??? because there is some benefit to him in doing it on ???, but that as far as the ????? is concerned, he could have chosen to do it during the week, or to do the same job on ??? without any ??????? (this is why the hired help can use hot water to wash the dishes on ???).
????? also does not apply, as DY correctly explained.
The real problem here, however, is not ????? or ??? ???. The real problem is that this is a total rejection of the sanctity of ???. The more a person bends over backwards to circumvent the ????, the more he shows that he views ???? as an onerous burden to be cast aside at the first chance. Please refer to Rav Belsky’s letter about the Kosher Switch.