The description of the Giant "Rocktopus" random creature encounter in the Out of the Abyss adventure (p. 28) provides the following details:
This creature is a giant octopus that has evolved to live and thrive on land. It can alter its coloration to appear as a rock formation, and it tends to lurk in crevices and fissures, attacking smaller creatures that wander near. It has a walking speed of 20 feet and a climbing speed of 10 feet, loses its Hold Breath feature, and replaces its Underwater Camouflage feature with the following feature:
Camouflage. The octopus has advantage on Dexterity (Stealth) checks.
The giant octopus (MM, p. 326) has a trait called Water Breathing:
Water Breathing. The octopus can breathe only underwater.
The giant rocktopus entry makes no mention of alterations to the Water Breathing trait, only to the Hold Breath trait. Does this creature still require an aquatic environment to survive, according to RAW?