Correct me if I'm wrong, but it sounds like you're making the point that there are lot of dumb people out there, so some miners and nodes will likely be dumb and set BU in ways that are unprofitable. Could be, but those same people might run XT or mod their Core foolishly.

For example, any smart miner running BU right now would want to mimic Core settings - unless they didn't mind losing money to make a point. If dumb people are the worry, set the defaults to mimic Core behavior exactly and include a scary warning not to change the settings or lose money. If they're dumb enough to still do it, they're dumb enough to send their coins to the wrong address, etc. I don't see dumb people as a big issue - do you?