I am not familiar with this specific case, but the Chief Rabbi is actually the Rabbi of the Non-Relgious.
If you are Gerrer, you go to the Gerrer Rebbe, If you are Belz you go to the Belzer Rebbe, If you are Litvish you go to Rav Shteinman or similar.
But if you are non-religious then you dont have a rav , so the Chief Rabbi is in charge of relgious life for those people.