Don't feel sad. I'm left handed, too and use fountain pens specifically. I hold my pens as a right handed person would, so my hand is very far from what I write, and I never smudge anything.

Hopefully you can impress on him that they are important to you, and rare, and while he may not use them, he can still respect them for what they are, and look after them

Hoping not to be culturally-deaf, you have an arabic sounding username, so maybe there is still hope for him if he decides to learn the language