If he did not have a child, sure. Suffering through this woman's wrath would be an opportunity to increase in virtue. But he is responsible for the formation of his child, most importantly spiritually..and he cannot let this woman influence the child. Him being a "wimp" could very well result in him losing his soul (i.e. "everything"). Him being a "tyrant" (what do you even mean by that? Exercising his God given authority over his wife and household? The wife is subject to the husband "in all things") could be what he needs to save his soul. He needs to start docuмenting everything yesterday..audio, video. Then he can put his "tyrannical" foot down and if his wife does not obey, he will hopefully have the evidence necessary to remove this woman from his and the child's life if it comes to that
But he won't have any power until he is back in his own country.
So though your advice might work, he can't do anything until later. He will probably lose the child to a foreign country if he is not patient. While he is practicing patience, he can docuмent everything.
I am not sure how saying no to her would go down right now because she has all the cards living in her country.
And to be clear, I agree that the husband of the family has the responsibility to lead his family properly.
The reason I ask for the good side of the wife is because I believe that he can use it as a tool to help calm their situation down. I really get tired of single men trying to give advice for the married state. Theory is useful, but sometimes you have to adjust for real life scenarios.