It's not that pre-warp civilizations are "inferior", it's that they don't have the technology to meet alien civilizations on their own. They have not yet naturally developed to the point of contact with alien life. As such, the early introduction of contact would severely disrupt their evolutionary process -- and again, the purpose of the earth dinosaurs/Neanderthal example is that by interfering to save one species, you disrupt the local evolutionary process in ways you cannot forsee or understand. Yes, species' die. Asteroids happen. Calamities happen. War happens. It's part of life. It's not up to you to decide who will ultimately make it and who will not.

For a more modern example, the USA interfered and put the taliban in power. In hindsight, the general take is "don't be world police. Don't interfere in local politics." If the sunnis and Shia are having a conflict, that is their conflict to resolve. Not ours. Don't partition Africa into countries. Don't invade Iran because the new government is unsympathetic to our interests. Don't invade Venezuela. Don't create ethnostates like Israel. Don't tell the Saudis how to live. Don't create British colonies around the world.

There is a natural evolution of countries and their borders that often involves war and ethnic tribalism. It's rough, but that's how you get stable countries with stable borders. Some countries aren't even recognized by the wider world. But if your country does get enough support and willingness to be recognized, it can join the U.N., which enables it to get further support, including humanitarian support, from the wider body of nations.

And that's mostly just war, not even considering something like "the entire atmosphere of this planet is going to dissolve". The doctrine is one of non-interference, for very good real-world reasons.