KR - not sure if I have your context wrong, but clearly vertical separation was not assured, and with the potential of the airborne aircraft going round, or the taking off aircraft aborting, separation can never be assured when two aircraft are converging to a crossing point like this. So don't do these pseudo LAHSO ops.
No, you did get it right. And you're also right in that such a scenario doesn't consider the 'what if the Pawnee goes around' in terms of separation.
But then this very same scenario is repeated many times at Bankstown (and probably other Class D's) whereby they'll send helicopters across the runway at 500 with aircraft on final - such that if the landing aircraft
does go around, you're now faced with an immediate separation issue.
Like this one.... And that's
with ATC - but of course, they also helpfully point out that
"This incident serves as a reminder to keep a good lookout at all times, including in Class D airspace. Pilots are responsible for maintaining separation in Class D." putting the onus squarely back on us if we smack into a helicopter we never even saw or that was passed as traffic, while conducting a go-around...