Not trying to defend the guy, but a Devil's advocate view and strictly hypothetically speaking (never happened to me )

ATC: got the preceding traffic in sight?
Heavy: Roger
ATC: Maintain separation, turn left/right heading 000 to intercept J99, maintain 10,000, contact departure on 123.54
Heavy PilotNotFlying starts twisting heading and altitude bugs and radio knobs and then begins the readback as PilotFlying calls for "Slats Retract, After Takeoff Checklist", and adds "What was the heading again?" And then you ask yourself, where's that traffic??

Let's see the original intent was to 'drain the swamp', right?

Usually, most days/nights it isn't a problem; but, every so often caution (and events) overrides reasonable expectations. Then again some guys just enjoy being the exception to every rule.