What is this guy saying?
He is nervous because there is solid proof that runs counter to the "politically correct" answers and agenda that has been forced down everyone's throats for half a century or more.
It makes him nervous because just by publishing this and doing this work, he expects the harpies of Political Correctness Hell to come out hopping all over his pale, pasty little balding head and make his life miserable.
That's not a pleasant prospect.
It's sort of like being a cartoonist who decides he's going to draw Mohammed doing obscene things and publish it. He might very well go ahead and do it, but he will worry, at least a little bit, that by doing this he's going to end up on his knees blindfolded someday getting his head sawed off by a serrated knife.