The Cardinals won't consider that because it does not really fit with what they envision.
That said, it is an interesting article and certainly something some teams might consider.
After all, more and more teams are simply asking starters to cover only 5 innings.
Converting a reliever - particularly one with Hesley's history (very effective minor league starter), frame (built like a starter, certainly), and 3-pitch arsenal (he can throw a curveball) - might be worth the risk.