Previously, before Taj had walked out, before Andy had resolved to finally kill himself, he would have already been there holding onto Taj so that he'd know that Andy was there. Now, watching his big brother curl in on himself, Andy wasn't sure he knew what to do. He wasn't sure that Taj needed him there any longer. He didn't know if he could be there; he wasn't sure if the start at seeing Taj which had knocked him out of his certainty to end his life had knocked the idea itself from him too, and it felt too much like lying to himself if he thought it had.
No amount of thinking could replace instinct though. Taj was scared and all Andy could do was what he did next, be it right or wrong. He moved towards Taj and then gingerly put his arms round him, tucking his chin over Taj's shoulder and holding on without saying a word.