Like maggots they had swarmed defilingly over the mystery of Linda's death, Maggots again, but larger, full grown, they now crawled across his grief and his repentance. He halted and, with bewildered and horrified eyes, stared round him at the khaki mob, in the midst of which, overtopping it by a full head, he stood. 'How many goodly creatures are there here!' The singing words mocked him derisively. 'How beauteous mankind is! O brave, new world....'
John's disillusionment with the New World, does, indeed, culminate in the Park Lane Hospital as the contrast between his true humanity and genuine emotion is set against the manufactured humanity of the Deltas who swarm around him. John realizes that Linda had "been a slave." There is no freedom in this new world from which his mother has come, a world in which the soul has been poisoned by conditioning and soma.
In a final heroic effort, as a culmination of his revulsion against the New World, John tries to free the Delta's from their servitude, but the riot police subdue this short-lived revolution. Having been defeated in his efforts to change the inhabitants of the New World, John is past his revulsion and only wishes for an escape in order to preserve his own soul. He asks to live out his own life in peace, but when photographers and curiosity seekers invade his solitude, John despairingly kills himself, as he, too, becomes a victim of the "brave new world."
Actually, I do not think it does. I think it reaches its limit at the end of the book when he kills himself.
However, you can say it reaches its limit here because he starts to physically fight back against the society. His revulsion is shown much more clearly here because he is actually trying to disrupt the society by interfering with the soma distribution and by fighting with all the Deltas.
The reason it reaches its limit here is because of John's human relationship with his mother. The society does not honor human relationships and emotions and John does. This is why it makes sense for him to lose control here. The human who was most important to him died and she died without even acknowledging him. She was too drugged up by the society's controlling drugs to even say good-bye to him.