We remember him for the few things he did right, not for the many things he did wrong. The 44 mag and the 338 mag were really important innovations. And he had some important cast bullet designs that still endure as good.
I've read many of his old "gun notes" articles and it's mostly rubbish, but he did have a lot of worthwhile things to read about. I am particulary appreciative of how he would tell on his own stupid mistakes, and this in turn taught me a number of things not to do. I think Green's Law applies: 90 percent of everything is crap. (Certainly 90 percent of what I do is crap.)
I'm not particularly a fan of Keith, but he deserves due credit for his accomplishments. Many of today's writers are better writers, but none have contributed materially as much to shooting and hunting.
As for trusting him, his hand load data is obsolete and has been for decades. It needs to be disregarded in favor of modern data.