His mother wouldn't drop dead, within his culture it is absolutely okay to take advantage of the dumb and naive, it's perfectly fine to take advantage of anyone outside of your own household, family, clan, tribe - particularly of "Westerners" (everything is allowed in the Dār al-Harb (House of War) which is the "West", the non muslim regions - of course Nadar doesn't know what the Dār al-Harb is, but he understands that he can do whatever to Western women). If he would tell his mother that this marriage would mean a house and good "income" she would be totally fine with a wedding. The mother knows that he is allowed to have other women on the side (it's not allowed within the teachings of the Quran, but culturally), so Chantals appearance doesn't matter to his family.
PS: In some clip she mentioned proudly that she already "met" his family (through facetime and I think there is even a video with one of his many brothers on facetime and Nader talks to him while she streams), but don't forget the language barrier, he can sit with her next to him facetiming his family and tell them in Arabic "Look, I found a complete idiot, I will send some money within a few weeks, don't worry about bills". She will just sit there and smile and giggle, not knowing what's going on.