Is pushing the child for this wrong?

This child is 6 years old and also autistic.

The scenario is the child is being punished for taking a key that she found that could have been dangerous. The child found the key unattended on a table in a classroom she was in and took it the key had a beaded rainbow wristlet with smiley faces on it and she liked the beads. She did not know what the key was for in her mind she is taking beads and not a key but the teacher said that the key was dangerous so she has to miss her playtime on Thursday afternoon.

She took the key on Monday and I brought it back on Tuesday she went to school on Wednesday but now she is going to be punished on Thursday during her last break time. I have punished her at home because other times when kids take things at school their isn’t punishments and they just say it is okay and to bring it back. It I have a problem with the delay in punishment if she had been punished for taking something immediately or the same day I wouldn’t have a problem. But when she took the key she was in an after school program on Monday and now she is being punished on Thursday at her last break time by her class teacher. It’s not sitting right with me. Because along with the delay they’re putting off punishment until it is convenient to them.

They said they were upset that she took the key because it was unsafe but I’m upset they let my child have access to this key that was unsafe. And if they feel like it’s okay to punish a 6 year old for taking what is essentially beads to her because she didn’t care about the key maybe whoever left these unsafe keys around children needs to be held accountable also.

I don’t have a photo of the exact keys but this is the kind of beads that were on this "dangerous" key that was then left where 6 year olds could get to it