If I recall correctly, when he was in Paris, he walked to Yves Montand on Sabbat rather than take a taxi. As a public official he represents all the people of the State of Israel, those who are Halachically Observant and those who aren't. Indeed, that principle was broken most "ceremoniously" when another serving Government minister catered a Hametz luncheon in Nazareth on Pesach, and was dismissed forthwith by Yitzchak Rabin, who was Halachically Observant, but understood that official events, no matter what they are, no matter where they are held have to show respect to all the citizens of the State, whether they are Dati, or otherwise.
Merkel says refugee crisis as challenging as reunifying Germany (Reuters)
from the article: Shimon Peres cancels Olympics trip over Shabbat observance