I read it more as that a dog with a great deal of self control is not necessarily a dog that is lacking in drive in any way. That steadiness should compliment drive, not counteract it. And that believing a dog has to be borderline/out of control to be a top class performance dog is untrue and does a disservice to the dog and the trainer.
However, it makes no sense to say that these intense dogs have "character flaws" because they have potential to redirect. That's like saying that sight hounds have "character flaws" because they might ignore your recall and take off after a rabbit.
I do think in any given breed there is a range of temperaments one can expect to see. we'll say there is a middlepoint can be considered ideal - a dog with proper drive for the job combined with just the right other desirable traits. Then there is a range of acceptable temperament in either direction that isn't ideal or has some temperament faults but isn't necessarily a deal breaker either. Probably no dog ever falls into the ideal in every way, there is room for improvement in all dogs. Some fall further from the ideal than others but where the line is drawn between acceptable and unacceptable often depends on the dog, breed, job and people involved. It is hard to imagine that a dog who repeatedly seriously bites their owner out of frustration or over-stimulation would be considered "ideal" or not having a temperament fault within any line of work though. I'm not saying that any dog who has such moments occasionally has a temperament fault. And I do think in some cases, it has as much to do with training/handling as it does the dog's genetic tendencies. I have seen people raise/train sport dogs in a way that encourages the dog to be almost constantly aroused, in the name of "building drive" and little to no work is done on impulse control. But I do think some dogs are very much genetically wired for such behavior too.