You're still making ground assumptions that this kind of technology turns out to ever make sense. If we invent transdimensional warpgates in 50 or 500 years, th

You're still making ground assumptions that this kind of technology turns out to ever make sense. If we invent transdimensional warpgates in 50 or 500 years, there may never be a faction left over that wants to play with steam-powered genetic plagues. The idea that you can seed the universe with civilizations in the manner described is highly dubious. You're assuming someone advanced enough to do this yet primitive enough to want to do it and that "it" works at all. Suppose that the galaxy produces one star system in a thousand with a suitable planet, and the seed has a one in a thousand chance of actually producing a successful replication. (Both of these one in a thousands seem to me to be quite optimistic.) The equations look a lot less deterministic.