As usual with these cases it is more complicated than it at first sounds:
I would not want someone to be carrying under the influence. So, the point is, do not carry if you plan on carrying-on.
However, I do not agree that just because a person has a medical marijuana permit, they should not be allowed to get a carry permit. (This is what the article is all about - whether someone who has a permit to use medical marijuana should be denied the right to get a concealed carry permit.) Just because you are allowed to use MJ, does not mean you should carry under the influence of your last hit.
And, of course, if someone misuses their carry piece while under the influence, they should be subject to criminal penalty, the same if they were drunk or high on prescription drugs.