I see this as the mitigating factor when it comes to negative outcomes to METI. If the first meaningful outcome is thousands of years out, doesn’t that probably give us thousands of years to evolve physically, socially and technologically to face the potential challenges of that meaningful outcome? Indeed, is it not likely that we will have a great deal better understanding of those potential challenges before they arrive?
It seems to me that the question of whether or not to METI is relatively minor compared to the question of what do we do about passive discovery in the meantime. After all, the earth is constantly emitting quite a bit of human produced electromagnetic radiation without METI. In the nearer term, it seems more likely that someone will stumble onto us than that they will set out to find us in response to an invitation and get here before we are ready for them.