Why didn't Long Feng just let Appa reunite with Aang sooner?

If only he would let Appa reunite with Aang sooner, Jet would sitll be alive.

Was Long Feng's evil cruel threat "This is your last chance... if you want your bison back" really Aang's l;ast ever window to ever reunite with Appa?

If only the Gaang could have tried to smile for Appa and NOT cry for Jet.

I wish Appa could have met with Jet one last time...

I expected Katara to loudly cry for Jet and say "If we had spotted Appa flying over Ba Sing Se sooner, Jet would still be alive!"

Of course crying for Jet when the Gaang have at long last reunited with Appa is not gonna bring Jet back... And neither is trying to kill Long Feng for it...