That was an interesting quote. I don't remember reading anything about the original or revised script for The Good, The Bad and The Ugly. So this was news to me.
The question: Is it more a drama or comedy. It's neither. It's an action western, as opposed to dramatic western (Unforgiven). Action films always have comedic aspects to them, like Dirty Harry, Die Hard, Terminator, and any of the James Bond films and more. It wouldn't in a million years be right to consider any of those films a comedy. But, if you can call any of them a "drama", then I would agree that GBU is more of a drama than a comedy.
My opinion of the script: Top rate. The balance of comedy to action is perfect.
This got me wondering, since all of the action films I mentioned above with comedic aspects may have been influenced by GBU since they all came after it. That's an interesting idea too, if anyone has any thoughts on that. Was it atypical to add comedic elements to action films prior to the Leone spaghetti westerns?