In terms of the AC Mains Equipment Grounding, it would depends on the maximum current failure for obtaining a certification of the electronics to be placed inside.
If the estimated failure current to the ground through the aluminum box is small, less than 10mA, the screws for the housing panel box should serve as conductors for the whole ensemble. If they do not provide enough conduction at the screw point, a conductive paste could help.
If the estimated failure current is greater than this value, which is the generally understood situation, and the case for Panel Boxes, every metal piece should be properly grounded. Even if there is an electrostatic, non conductive painting for the whole set. Note the standard details shown in the picture is factory welded and painted, with ring wire terminals.
In terms of RF Blocking, this should be supported with a proper calculation for estimate the RF energy emitted outside the box. This is a bit outside the scope of the question, and will require a RF Calculation, RF Modelling or RF Laboratory Testing.
In this case, the ground looping concept is not applicable, because there is not a current loop flowing, nor electronics components exposed to that loop.
At the end, for both two cases, this requires to be in touch with your Certification laboratory in order to know if they are currently accepting using the same mounting screws plus conductive paste as conductive elements. Finally, they will be the ones approving or rejecting your product.