Most certainly. The appropriate punishment here would be nothing however. A player may concede a game or match at any time for any reason as long as bribery is not involved.
Official Tournament Policy:21. Game Concession
Players may concede a game or match at any time, provided that the concession does not involve compensation in exchange for the concession. Players may not offer their opponents any type of compensation or bribe in exchange for a concession.
Andy Danielson
World of Warcraft Rules Knowledge level 1
Player Management level 1