A few quotes from the Rabbi on 'Israel and the Nations'
in which he teaches that customs should be changed and the custom of the nations to rise when blessing the king should be followed
Although the customary blessing of His Majesty the King was once recited before the Ashrei Yoshvei Beitecha psalm, and this ancient custom has been observed here in Izmir for three hundred years, it was nevertheless moved and is recited when the Torah scrolls are taken out of the ark…Since it is the custom among the nations in all the cities under his dominion to rise when cheering His Majesty the King, we, the Sons of Israel, who are also the subjects of His Majesty the King, may his dominion endure, must rise when reciting the Blessing for His Majesty the King; we are to follow the customs of the nations of the world. Israel is to learn from the customs of non-Jews.
VaYosef Et Ekhav, Ma'arechet Beit, Section 3 p. 15b, Hacham Mordecai Barkai, Izmir, 1896