Tufguy, it's very unnatural. We wouldn't normally say a person is honest at work. (Is he dishonest other places?) As for being genuine at speaking, I suppose that means he tells the truth.
Saying someone is "an honest worker" is an expression. It's no so much that they don't steal things or lie (but that is sort of assumed), but that they work when they are supposed to work and don't slack off or goof around.
Saying someone is "an honest worker" is an expression. It's no so much that they don't steal things or lie (but that is sort of assumed), but that they work when they are supposed to work and don't slack off or goof around.