If you’re asking the group, my answer would be: make it a customization option.
I can see why some communities would want to allow this. However, in my experience, preventing users from updating closed topics often encourages them to look for an existing active topic or start a new one instead.
Another option would be to preserve the “Me Too” signal even when the topic is closed. For example, if a user clicks “Me Too” on a closed topic, they could be offered a simple option to open a new topic, after AI first checks whether there is already an active topic covering the same issue.