Teamwork

In the end, Malachi joined his family in taking the crystal hearts of the zombies from their chests with a smile on his face. What he had feared didn't manifest. 

Anna didn't hate him. David didn't hate him either. Mia didn't hate him as well. 

None of his family gave off the feeling that they were even disgusted by his actions of taking crystal hearts from the chests of the zombies who were formerly once humans. 

Malachi could tell they were disturbed by it though, but it was more about the action taken than who, which in this case was him, who took the action.

Even though it was only the second day of the apocalypse, it seemed like his family understood that to survive was not something that could be done by convenience. They had to take certain actions whether they liked it or not, whether they wanted to do it or not, for the sake of survival.