I would feel uncomfortable with a precedent in which subsequent action on the part of the victim (in this case suicide) has a direct impact on sentencing. In a small number of people it might end up being a motivation to go through with a suicide they otherwise wouldn't have - they won't feel that they will get the full justice they deserve otherwise. That is not to say the perpetrator in this case should get off lightly - to my mind the 'throwing a corrosive substance with intent' charge should carry a sufficient penalty to cover the possible eventualities anyway.