If the advert is the one I think you mean, then it was made ages ago and is run at intervals, and was not directly put on in response to what has just happened.
Personally though , thinking about it , big businesses target their advertising to events,because its cost effective. It works. If we want our charities to use donations most effectively, isnt it good that they also use their advertising budget to proven best effect?
All that matters is that it gets to the right people who WILL benefit from seeing it .If its uncomfortable for anyone else who sees it, so flipping what? The only danger is if those people react to the discomfort of seeing it by using it as an excuse not to give their money. That would be perverse though--- but could be why the NSPCC DIDNT target this ad to the event in question.