As Dennismn so correctly points out "For that matter the same argument can be made if a J-frame revolver is fired too close to the body". Wonder why those experts that show outrage over ports on the Shield never manifested itself against those that carry revolvers for self defense, as hot gasses escape from the gap between the front of the cylinder and the barrel, as anyone who has ever let their fingers get close to that area well knows.
There are no alternatives with the revolver and you do indeed have to mind the revolver B/C gap in certain instances-such as with how you grip the weapon and holding it against the torso, but there is no need to cant the revolver when shooting from retention as you have to do with an autoloader. Disrupting vision is the primary concern and you would have to hold the revolver pretty much completely sideways and abnormally high to remotely become an issue with venting towards the face and eyes.