Because if the sentences they spoke simultaneously were still the same, then the three of them would still be under the control of their combined power.
The other Survivors who saw the incident could only remain silent and do nothing. Hector's older sister could only stay where she was, watching her younger brother use his powers to wake up his friends.
Because for now, that's all he can do to help his friends, even though he knows many people don't like him and his little brother.
"I know he has extraordinary power because I can feel it since I healed him. And I think that if he is with his older sister, he will become a great partner in the future." Alexis said proudly because the two Disciples she taught could use their powers well; although many disliked them, they didn't do the same to their other friends.