That would carry more weight if ws had actually gotten word that they are dying out. The people are well aware of their importance and they won't suddenly die out.
Also not as helpful because it would be us having more Carrion Eaters not the March and since we aren't sending them support...
Forest on the other hand is taking care of long term. They will be taking Chariots this turn to better their martial, but that only helps against immediate raiding. The sooner we start the forests, the sooner we have them as protection. Especially since they can then use the Econ it gives them to grab Carrion Eaters of their own.
If they need Carrion Eaters, they will purchase those for their own use as well as Warriors to garrison their town and boost their numbers.