Well, I'm going to voice the same concerns brought up in the FB comments:
1. The color spectrum is, intentionally or unintentionally, biased. Using red, orange and yellow for positive based training preference is giving off subliminal "warning", " danger", "caution" signals and is suggesting negative, emotional and knee-jerk reactionism. While using green, blue and purple for the other end is suggesting calm, mature and thought out processes.
2. The rising of the chart as it moves towards the purple is also indicating a bias towards the purple end.
3. The use of "purely positive" for the red end, while avoiding terms like "aversive", etc at the purple end, is again biased. It is stressing training method limitations used at the red end while evading the extreme training methods used at the purple end.
4. The descriptors are misleading and biased. They suggest that those towards the red end train using only one method (giving treats) for all dogs in all circumstances while those towards the purple end are "training the dog in front of them" and are more willing to adjust their methods. That suggestion is completely untrue as there are trainers on the purple end use one method (punishment) for all dogs in all circumstances while there are trainers on the red end who will adjust their methods for a specific dog in a specific circumstance.
5. While the paragraph below the spectrum indicates that the color you identify with is based on the tools you use, no where does it really indicate what tools fit with what color. Instead it clumps all tools (clickers, flat collars, harnesses, prong collars, e-collars, leashes, etc) together as if they are all equal. The only tool it singles out is treat rewarding. And that is done in a biased manner (see points above).
6. It fails to incorporate all the other aspects of training such as counter conditioning, resolving issues underlying unwanted/inappropriate behaviors,, setting up for success, praise, etc.
In the end, I think it is a passive aggressive justification for those who consider themselves in the green and blue sections. It dismisses those n the yellow to red sections as emotional, limited, and less than desirable. While it singles out the purple as purely negative, it puts all other corrections and punishments in the "good" green and blue sections. And, just like the term "balanced trainer", it suggests that using aversive tools like prong collars and e-collars is good as long as you also reward good behavior regardless of how much of either you actually utilize on a regular basis.