There are lots of folks who aim with the LEFT eye, although most dSLRs and 135 film SLRs ever manufactured were designed with a shorter body to the left of the eyepiece than to the right of the eyepiece, a feature intended for RIGHT eye aiming. Similarly, when you turn the body CCW to change to Portrait orientation, the left eye remains clear so that it can see around the camera, rather than the right eye view being blocked by the body in Portrait orientation.
(And we should not forget that the Battery Grip presents buttons for us to use with CCW Portrait oritentation, while those buttons are not positioned well with CW Portrait orientation.)
Use of left eye is is not 'wrong' nor is CW Portrait, but it is using the camera which is suboptimal based upon the camera product characteristics. The original M16A2 was poorly designed for left eye aimers, too; you needed to be able to tolerate hot brass cartridges doing down your shirt.
As for eye open vs. closed, I learned in high school the value of left eye open, which shooting a football game on the sidelines for our high school newspaper. I was so engrossed in capturing an end run by a running back (with my eye closed) that I did not see (a good friend) offensive guard running at me and bowling me head over heels with my camera. While I was not injured, I learned what an open eye could do so save my e$$ from another experience like that!