I have heard of people stealing bits of code from other websites, layouts, patterns, interactions, you name it.
To be honest, from time to time, I don’t know how to solve a problem and I look how the competitors are solving that issue. If is good and applies to me, I use the same approach.
But stealing a whole project and pretending they did it, is outrageous.
You shouldn’t link his portfolio, instead, post his name so is the first thing that appears when you google their name.