Most of the results regarding handball refer to defenders, however, I would interpret this as universial to attack and defence. In this case I think it's fair to say that the handball affected West Ham;Does it actually say that in the laws of the game? I'll agree it would be deemed "iffy" but if a defender can accidentally handle without being penalised why can't a forward.
http://www.thefa.com/football-rules.../football-11-11/law-12---fouls-and-misconduct"...Where a handball affects the opponents it should be judged like a foul"