"Allow search engines to index this page" is an option for the external search engines like Google. As you might know all backend pages are located under /sitefinity. As a structure they are the same as the frontend pages, however the Sitefinity's sitemap treats them differently. The backend pages have certain type of permissions applied to them by default and Sitefinity does not allow search engine crawlers to index them. This option for the backend pages is used only for the internal Sitefinity indexing engine. Because the backend pages are the same like the live pages, but with different permissions, they all have equal editing template.
If you want to save the changes of the backend page with the default content of the "Allow search engines to index this page" field you can simply modify the regular expression for that field. In the attached files you can find where is the regular expression for that field and you have to change.
the Telerik team
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