I have not driven the road, but I have flown over that road many times in the past month, following a route from Nairobi to Lokichokio (Loki being quite close to Lodwar).

There is quite a bit of truck traffic on that road, and I don't think you would have any problem getting through with a 4WD or a dual sport moto. You might have some difficulty getting gasoline (all the trucks run on diesel), and you might also have some difficulty finding a suitable place to spend the night, with appropriate security for your moto.

But - so far as personal security on that road goes - I don't think it will be a problem for you during the daytime.