I don't agree with BJD being contagious. There is no way it can be... as a physician, I will tell you that bacterial infections are NOT contagious. They can only create issues if the host is immunocompromised. I've have a full euphyllia tank (more than 3 dozen coral) and have not experienced anything of the sort, even though I've had, just like others, corals die of BJD.
If the other corals are well maintained and are established, BJD won't effect them. It will destroy the colony, but not other corals. It has to do with coral immune systems and the ability of said coral to fight off any infestation from bacteria. Any slight damage to the tissue will cause demise, not unlike human skin getting infected after a cut.
Yes, you can get pests, but if you observe the coral and watch for pests...
Having lost more than my fair share of euphyllia to BJD, my success with it changed dramatically when I stopped trying "to do what I can"... once I stopped dipping and stressing the coral even more than it was already stressed, my success has improved dramatically.
I know I'm out in left field on this, but from a clinical standpoint, it makes perfect sense. No different than someone being hospitalized for bacterial pneumonia; not everyone in the household gets the bacterial infection.