Two-Bit was relieved when Ponyboy picked up the broken glass because?

Two Bit was worried when Ponyboy broke the glass because it showed that he'd become desperate and hardened. He was relieved when Ponyboy began to pick up the glass because it meant that Ponyboy was not permanently changed. The simple act of picking up the glass illustrated his sensitivity. Two-Bit is relieved to see that Pony is acting like himself again.

"Ponyboy, listen, don't get tough. You're not like the rest of us and don't try to be..."
What was the matter with Two-Bit? I knew as well as he did that if you got tough you didn't get hurt. Get smart and nothing can touch you...
"What in the world are you doing?" Two-Bit's voice broke into my thoughts.
I looked up at him. "Picking up the glass."
He stared at me for a second, then grinned. "You little sonofagun," he said in a relieved voice. I didn't know what he was talking about, so I just went on picking up the glass from the bottle end and put it in a trash can. I didn't want anyone to get a flat tire.