Two days yom tov

Question

I have a friend who is an Israeli citizen born in the US. He now lives here after spending many years in Israel. Although he has aspirations to return to Israel, he is clearly not doing that at this point nor does it appear that this will happen anytime in the near future. He holds only one day yom tov and I have questioned him about that. My belief is that since he is now clearly based here, he should be holding a second day. What is your psak on thsi issue, one day or two?