You can check the content that is sent to the server by toggling between Design
mode of the editor. If you do this you will see that the <noscript> preserves. Unfortunately the described behavior is another problem caused by the MOSS content filter. When you submit the page, MOSS will validate it and automatically make changes if the content is not valid. You can verify this by trying to enter the same content with the original SharePoint rich text editor.
We have not been able to find a workaround for this behavior yet.
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