Do you actually want “the most competent” people in the senate though? At least in my mind a government delegates optimization problems to the civil service and the elected officials are more like “alignment”. So them being too old could result in issues relating to older people having priorities that are not quite lined up with the overall population, but similar issues could equally arise from them being disproportionately rich/poor male/female minority ethnic. Ideally the senators are setting targets and checking that the civil service is pursuing these goals without simultaneously doing bad things.
Do you actually want “the most competent” people in the senate though? At least in my mind a government delegates optimization problems to the civil service and the elected officials are more like “alignment”. So them being too old could result in issues relating to older people having priorities that are not quite lined up with the overall population, but similar issues could equally arise from them being disproportionately rich/poor male/female minority ethnic. Ideally the senators are setting targets and checking that the civil service is pursuing these goals without simultaneously doing bad things.