This isn't a very good argument. What if his composition was top notch to begin with? Then improving his image quality may very well improve his work. Blanket statements from either side in this argument aren't very helpful.
I suspect you misunderstood my point, and I think you might find that we actually agree ;-)
You should agree sir, that if the comp is craap, then the higher image quality will also be craap. This is true every single time.
Now if the comp is great, then the higher IQ makes it even better. This is true too, every single time too.
Two blanket statements that are true every single time ;-)
Here's a 3rd blanket statement that is true: A better kit will not improve one's compositional skills. If it did, then I'd replace my two 5D's with one 1DS Mark III...wish it were that easy ;-)
Photography is a subjective art, that is build on the foundation of some objective methods, truisms, and blanket statements ;-)
What may well be subjective is the term "better camera". For a given vision, result a $30 Holga with a plastic lens might be the "better camera" because it offers the less then perfect look that the $8,000 1DS Mark III might not be able to provide, if that look is what one is wanting.