Well, at least you called it CO2. One point up for using it's actual name, instead of that dirty word, "carbon" that has caught on so strongly lately.
Why "intellectually dishonest"? What does that even mean? If somebody argues a point that you don't agree with, it's "intellectually dishonest"?
You've already defined the game so much to your benefit, and we're playing it to your rules. When you ignore water vapor, we let you. When you ignore what everybody knows, that the climate is warming regardless of human contribution, in the endless climate cycle that's 4 billion years old, we let you. You've defined the game to be, humans are causing extra global warming (you leave out the 'extra') and we let you. We've handicapped ourselves quite severely in this 'debate', so that you'll at least play with us. That you take advantage of this handicapping with not even a "thank you" is what is intellectually dishonest.
So, this author makes the claim that there may be benefits to warmer climate. He's playing your game. He's bowing to your religion, by saying the words "warmer climate". But you're not happy. It's intellectually dishonest.
Every action has costs and benefits. Obviously there would be benefits from a warmer climate. It's intellectually dishonest for you to claim otherwise. Do they outweigh the costs? I honestly don't know. We're a global community, right? A longer growing season in the temperate latitudes vs a shorter growing season in the tropical. Does this result in more food or less? I don't know (although I suspect it does). More people running their AC in the south vs less people running their heaters in the north. Is this a power savings or a power sink? (I suspect this ones goes to you, as heating is more efficient than cooling). There's a ton of analysis that could be done here, before you know the answer to this question. For you to just say "intellectually dishonest" without considering any of it is perhaps a result of your bias.