Riot is just covering all their bases

Riot Games shall not be liable for any delay or failure to perform resulting from causes outside the reasonable control of Riot Games, including, without limitation, any failure to perform hereunder due to unforeseen circumstances or cause beyond Riot Games’ control such as acts of god, war, terrorism, riots, embargoes, acts of civil or military authorities, fire, floods, accidents, strikes, or shortages of transportation facilities, fuel, energy, labor or materials.

from the terms of service