if you set up shop on an underpopulated realm, it could be destroyed or turned into a different kind of server,
Okay, I get that.
so you'd better transfer to (or roll on) Tichondrius or Mal'ganis instead and let Blizzard deal with the load issues.
But I don't see how you arrived at that conclusion. I think maybe I'm starting with different assumptions: people rolling on low-pop servers are doing so for reasons that would never make them want to roll on high-pop servers in the first place.