Somebody simply needs to teach him to hit the correct lines. And it doesn't matter whether that is a cyclist, a biker or a baker. But chances are that somebody who is used to take those lines, and is able to spot them and decide to take them at 200km per hour, a few hundred times per hour will know what he's talking about.
It is his main issue on the bike, cornering. And this becomes a real problem in descents and on technical circuits. For all other issues, like bike handling, obviously yes, a cyclist would be a far better coach. For this specific problem, his main issue, no not really.
They are related. There is seeing the corner with your eyes, and there is seeing the corner with your brain (reading the corner). When you don't see the corner, your brain automatically makes the wrong decision in a reflex, to steer into the corner sooner, because your instincts fear of going out of the corner on the outside and your fear dictates to get away from the outside of the corner. This is always what happens. The result is the exact opposite, because by steering into the corner too soon, you have cut yourself off of the ideal line and are now headed straight for the outside of the corner. Your only option now is to hit the brakes and hope you don't crash.