Grandparent said that the law doesn't say that "a and not a" is always INvalid. (The law also doesn't say that "a and not a" is sometimes valid. It makes no comment at all, but only claims that "a or not a" is always valid. According to the grandparent. Now I need to lie down for a bit....)

Yes, this.

The point was that you can reject the law of the excluded middle without getting into the absurdity that would result from accepting "a and not a".

Ahh! Now I see I misread your comment, I see what you were trying to say now.