About the not interfering with internal affairs: If someone is committing genocide, do you just stand by and watch while millions, possibly billions, of innocent people are killed? Of course not. If you do, you cannot call yourself morally superior to others. Now I'm not saying its okay to interfere with every internal affair, but if its something like genocide then you should try and stop it.
You have to use realpolitik in these situations: IS it possible to really affect anything here, and if you have to resort to military force to do anything then will it be worth all the resources and lives of your OWN CITIZENS for it or will it only result in MORE death?
Sometimes you just have to know when to fold em.
They claim to value all life. If they truly value all life as they claim to, they'd be willing to make a sacrifice to save the lives of innocent people.
sonak is also correct that the Federation will turn a blind eye to a natural disaster even if it would wipe out the species. Specifically if it was a pre-warp civilization. We see this in "Pen Pals" (TNG). Picard does not want to help the civilization, even though billions of people could die.