Since you brought up Derelict:
In Derelict the Lucifer destroyer was stuck in subspace (it still had its reactors) and when it came out of subspace it didn't have its shields. Also, it wasn't destroyed by having its reactors destroyed, a Helios-stuffed Deimos rammed it. (I think by this point most know how Derelict ends but if you want me to spoiler this part I will)
Bringing it somewhat back to Scroll:
Since Derelict didn't have shielded Lucifers, basically we don't have enough canon information on all Lucifers and its up to the campaign creator to decide whether future Lucifers would have shields or not? Derelict chose one way and Scroll chose another.
That's an interesting opinion he had on the FS1 Lucifer. Like you, I'm not sure I agree with it, but he's at least made a good effort to justify his position.
I hope I haven't sidetracked things by bringing in Derelict comparisons. I'll have a specific Scroll post later.