Not a bomb expert, but a laptop is just a bunch of electronics next to a solid mass (for the battery). A bomb is also just a bunch electronics next to a solid mass (for the explosive).

>I mean, what's the other option - would they arrest a person carrying non-working/for-parts hardware?

I doubt they'll arrest you, but I vaguely remember airline websites saying that any laptops you bring MUST be able to turn on so they might confiscate it.