No, he's referring to the soft reload added in 1.5, which the article you linked addresses under "Just Reload HAProxy." As the article points out, it's not quite zero-downtime, but pretty close.
The DNS resolution work that is going into 1.6 releases may lead to a workable approach where you over allocate servers in a backend and then update them to have the right host/port. Last I checked, however, you still couldn't set the port dynamically.