Sounds like you have no realistic idea of switching noise propagation. The said electrically "hot" heat sink must be expected to couple capacitively into high impedance circuit nodes and possibly also radiate EMI. But it hardly affects low impedance nodes like the gate circuit dierctly. The strongest coupling between switching drain and gate node is inside the FET, by the way.
Another effect to be considered is that capacitive loading of the switching node causes ground return currents which may affect the control lines to the gate driver and the control circuit in general.