this is not even a laptop issue.
Why would BOTH of them be actively working on something that is NOT FLYING THE AIRCRAFT?
Missing a check point is one thing, missing a silently flashing error light is quite another.
Even if they didnt have a laptop in the cockpit doing this ****, they could have been as easily distracted with a clipboard and slide rule.
The only mitigating factor I see here is if Delta expects them to do all this rostering **** but doesn't provide a logical timeframe for them to do it (i.e. it's all due at the end of a flight but there isnt a logical break for you to do it in -other than your bathroom break) then it can be inferred that it MUST inevitably be done in the cockpit somehow