He is correct,however it is rabbinic & would not require a death penalty only whipping.
Obviously Rabbinic Laws don't apply to goyim. However, goyim are required to set up a court system. So if a Non-Jewish country would enact a prohibition of lesbianism, it would have the status of Dina D'Malchuta Dina, and goyim living in that country would be required to keep those laws and face civil penalties for engaging in that type of behavior. I guess the civil laws would be equivalent to the Rabbinic prohibition but most countries allow even male homosexuality. I guess in Muslim countries, women would be required to abstain from such behavior. But then again Sharia is religious law so I don't know if it qualifies as setting up a court system in Gentile countries. Shariah has other issues that violate the Noahide Laws such as permitting murder and stealing against infidels. So therefore I don't know if a ban on lesbianism for goyim actually applies anywhere.
Of course Christians can make up their own laws about it but I don't know any Christian countries that apply religious law as law of the land. Most Christian countries are now Liberal Left Wing countries. Even in England, where is there is a state Church, they allow homosexual marriage.