Not really, the whole point of the prime directive is to not contaminate an alien culture with knowledge and/or technology that influence them in their natural development.
So the plan was to help them without them ever knowing they were in any danger.
Picard's (in)action in similar situations was more or less based on that he didn't believe saving those 2 cultures could be done with cultural contamination.
He was proven right, there was a hefty price paid in the end.
The question really is, if it is moral to not intervene when the harm done to the culture is complete annihilation.
I'd say it is not, but where do you draw the line?at what point does it become acceptable to let things play out on there own?
A volcano that kills a continent of natives? A single region? Just one tribe? A village? One person?