"[The DOL] notes that 'unlike the proposal, the final rule's operative text contains no specific references to ESG or ESG-themed funds.' Rather, acknowledging the fluid definition of environmental, social, and governance factors, the [DOL's] position is that 'the lack of a precise or generally accepted definition of 'ESG,' either collectively or separately as 'E, S, and G,' made ESG terminology not appropriate as a regulatory standard.' Therefore, the final rule ... refers to 'pecuniary factors and non-pecuniary factors' in defining the relevant fiduciary investment duties."