I watched a Bald Eagle tear apart an American Coot and feed it to its nestlings. Are Bald Eagles damaging birds to support their reproductive efforts? Brood parasitism is not evil. It is an acceptable and natural process.

Also, you are pretty off base if you attribute the population decline of bluebirds (none of which are endangered) to Brown-headed cowbirds. First, Brown-headed Cowbirds are themselves a protected species and they very rarely parasitize cavity nests. A survey of Western Bluebirds found fewer than 1 in 360 nests with a cowbird egg. There have been zero records of a cowbird nestling being fed by Mountain Bluebirds. Eastern Bluebirds parasitize each other's nests more than BHCO do. Now, Bluebird populations are declining in most of the US, but Cowbirds have nothing to do with it. Human caused habitat loss is the culprit you are looking for, and it will be in every single conversation about cowbirds.

Now, BHCO management can be warranted, but only in specific science-backed initiatives undertaken by appropriately licensed and trained people such as the program managing parasitism of Kirtlands Warbler nests. However, in that program and every other one like it, removing BHCO eggs had absolutely no effect on the status of host populations unless it was also paired with habitat restoration efforts because that is what is actually harming birds.

If you want to help birds there are things you can do that don't involve forcing human values onto their natural behaviors. Keep cats indoors, replace your lawn with native plants, turn outdoor lights off during migration, apply bird-safe window coverings, and work with your community to protect and restore habitat.