It had to be done.
In this extremely rare case, the entire universe depended on Batman's action.
It was very obvious that Batman cannot defeat Owlman straight up thus it was impossible to capture Owlman alive AND stop the bomb.
Batman simply took advantage of the opportunity that Owlman gave him. It was one shot to stop him or face the end of the world.

True, but it also means another Owlman chose to not press the abort button and eventually froze to death on a barren planet.
"Need" is a man-made concept. As is "should", "must", "value" and "importance".

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Exactly.
Can't stop the signal.

Whether teleport or not, the "Abort" button was still blinking for a few seconds before the bomb was set off. He decided to die.
If you're hungry, try a piece of your friend!

Owlman could've teleported out. He chose to stay. He killed himself.
How did Superman kill Johnny Quick?
Straightedge means I'm better than you.