Up to what point is the ''I was a stupid kid'' a good excuse to be mean?

I'm not sure if anyone of you saw the movie ''You Again''. That pretty much covers that excuse.

The lady is now in her mid-late 20's and finds out her brother is about to get married to her old HS bully. He's going to marry the woman that tormented at school for 4 whole years. When the woman is confronted with her past, she said ''I was a stupid kid'' and ''That was HS''. She had no intention of ever apologizing and at the end, the apology was forced.

Up to what point is that even a valid excuse? Or should people move on from HS?

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+1 y
The former bully expected the lady to just forget about the HS issue, move on and speak to her as if it never happened.
Up to what point is the ''I was a stupid kid'' a good excuse to be mean?
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