...or like The French Laundry?
Admittedly, I had to Google this to know what you were talking about, but I'm intrigued.
Let's look at another, perhaps extreme, example.
Say I brew an IPA that isn't quite what I had in mind. Say I would like it to be a bit maltier and a bit darker as well. So I purpose brew a brown ale that would A) allow me to blend with the original brew to get the characteristics I want, and B) stand on it's own as a quality brown ale.
After brewing, I find a 6:1 ratio of IPA to Brown gives me the malt character and the color I'm looking for. Is this cheating?
I would, personally, commend a brewer that did this. I think it would take immense skill to be able to troubleshoot a beer like this, and create a whole other brew in and of itself to make up for the inadequacies of the original brew. I would love to sit down with that brewer, if possible, and talk about how he came to those conclusions, maybe even tasting each individual beer as well as the blend.
This may be a bit outside the original intent of the OP, but I think the fundamentals of my argument show that there is no foul play going on when blending beers.
EDIT: Respond to another post
It’s a little late to add another specialty grain to the mash. Unless blending your final product with another was part of your plan, your recipe is locked in.
Why? What difference does time have in any of this, you're adjusting your original recipe to make the best final product, who cares if it's 1 hour later, 1 week later, 6 weeks later, or a year later. You are challenging yourself to make the best possible final product.