Article is espousing the benefits of asynchronous communication. If the expectation is that I respond within a minute or so, then it is synchronous.

Can you suggest a better way to use IM that doesn't require me to respond quickly?

I'm fine with IM for sending over quick URL's, etc while doing a live debug or something. But if you just have a "quick question", email me if not urgent or come to my cube if it is. If you are located far away, call me. Both email and phone are more efficient for simple questions. IM is in the unhappy place where it's worse than both.