If you are using tuned or ktune (for example, if you are running Red Hat or CentOS 6+), you must additionally configure them so that THP is not re-enabled. See Using tuned and ktune.
This is not 100% accurate. Disabling THP in tuned/ktune is sufficient. The motivation for disabling in both places (inti.d and tuned/ktune) is because conflicting settings can overwrite one another. But if THP is disabled in tuned, as long as it is not explicitly enabled in init.d, disabling in init.d is not technically necessary for THP to be disabled.
If the documentation is going to recommend both steps, it might be worth clarifying that the reason is to prevent a conflict. Otherwise, a reader might question why both steps are necessary.