Nah, this is bs.
Plenty of people are fueled by anger, motivated by anger, focus better when they're angry. Anger can already be cold and calculated, no transformation necessary.
But aside from all that, emotions don't have to be productive. They aren't productive or unproductive, they simply are. Emotions are largely involuntary reactions to our surroundings and circumstances, a lense that colors an individual's world. They're all valid, regardless of whether or not they're productive, and pointing out that "anger is not productive" makes you part of the problem the post is describing.