I'm not trying to dismiss what you're saying as a possibility (AMD's behavior in many regards over the last 15 years or so is baffling to the point that a family conspiracy feels surprisingly plausible) but Huang isn't Su's uncle.
They are "first cousins once removed" meaning that Su is the child of one of Huang's cousins. Or put another way, one of Huang's grandparents is one of Su's great-grandparents.
Honestly, my mind could never wrap around genealogy and family relations well at all. I thought they were indirect cousin/uncle , or as you say, cousins once removed.
Also my understanding of many Asian cultures is they tend to have a much more tight-knit large family structure. And doubling that is the fact they're 2 heads of world-level hardware tech companies.
And, well, there's no such thing as coincidences. Having all of this line up, and for "some reason" AMD keeps missing when they could have owned a big chunk of the market has a certain family oligopoly smell to me.