I'm sorry what?
"1 – Islam (i.e., the ruler should be a Muslim), because this is a condition of testimony being acceptable and guardianship being valid, which are much less serious issues than rulership. Allaah says (interpretation of the meaning):
"And never will Allaah grant to the disbelievers a way (to triumph) over the believers" [al-Nisa' 4:141]. And rulership, as Ibn al-Qayyim said, is the greatest of such ways. And he is to take care of the interests of the Muslims. End quote.
Based on this, it is not permissible to swear allegiance to a kaafir ruler, and if the ruler becomes a kaafir then he should be deposed, according to the conditions that are known to the scholars. "
https://islamqa.info/en/82681
Your link is dead by the way