You don't understand how I tell a true story that actually happened? It's pretty easy, you start with facts and go from there. That's what I keep saying!
Whether or not WRT54g is running Linux under the hood, it's pretty specialized hardware. Definitely different than what you'd have in a standard desktop/server. That's the best explanation I can think of for the difference, but who knows? Whatever the case, I'm not going to take the effort of setting up PPPoE on a gateway machine when the potential consequences outweigh the benefits.
And for what it's worth, I'd gamble that the people running the box have more Linux experience than anybody here. They definitely knew what they were doing. It's pretty hard to cause kernel panics with stock systems by simply not knowing what you're doing.