I think in practical terms what this means is that in the case of an unexpected absence or resignation by someone who was an agent of Parliament, rather than name someone from outside the organization, there would be an interim role played by somebody who was in the organization, who was a public servant and who met the language requirements of the senior public service.
Dans les faits, si un agent du Parlement s'absente ou démissionne inopinément, il vaudrait mieux, plutôt que de nommer quelqu'un de l'extérieur de l'organisation, confier le rôle de façon intérimaire à un membre de l'organisation qui satisfait déjà aux exigences linguistiques applicables aux niveaux supérieurs de la fonction publique.