It was just that, at such a critical moment, whether their bodies suddenly grew larger had clearly become irrelevant compared to survival. In the face of staying alive, matters like that all had to take a back seat.
Steve, standing to the side, saw the change in Peggy Carter, and hope reignited in his eyes. Silently, he prayed for Robet and Peggy Carter—and for Brian, the child who was growing up.
As for which god Steve was praying to, that was impossible to know, but presumably, it was no longer any of the conventional gods.
The clash between the Healing Spell and the Reality Stone was a long process. Robet also knew that letting things keep draining away like this was one thing, but after confirming that the Reality Stone did not intend to kill Peggy Carter and Brian outright, he acted decisively.
With a buzz, Robet's ki joined the battlefield, becoming a third force. Though it was called a third force, ki and the power of the Healing Spell were originally one. The two complemented each other: the ki expelled the Reality Stone's power, while the Healing Spell restored the two injured bodies.
Robet also had to admit that the Infinity Stones were indeed formidable. His current rate of consumption far exceeded when he had only used the Healing Spell before; it had even reached the point where he was spending more than he recovered. Even so, Robet continued to hold on, because he also wanted to know whether something like an Infinity Stone actually had a limit...
Unfortunately, Robet was unable to probe the limit of a single one of the Infinity Stones. After the Reality Stone left enough fragments inside Peggy Carter and Brian, merging them with their cells, it had no intention whatsoever of continuing to