I would argue that people stay out of the STL urban core because they are afraid of it, not because MetroLink screwed them over. People will definitely move due to poor schools and school district policies. It has a larger effect on their lives personally. But taxes for things that they may never utilize? Not as often. Houston and Charlotte recently built light rail systems that are, right now, pretty small relative to the size of these very sprawly, suburban cities, and yet they continue to grow and prosper.
It would be incredibly poor urban planning to completely neglect parts of the city from transit. This BRT line, while they may not mention it right now, is likely a starter line for a more comprehensive transit service. Transit systems like this are always built in phases. It's not going to go to Gretna immediately.
ReLo people show you homes based on what you say you're looking for in a community. If someone says "I hate cities with currently uncomprehensive transit systems and paying taxes towards them", then yeah, I can imagine they'd take them to Sarpy. And they should, as I've argued. ...But who says that?
"Video game violence is not a new problem. Who could forget in the wake of SimCity how children everywhere took up urban planning." - Stephen Colbert