After further explanations: on mediawiki.org where Structured discussions are default, it is possible for anyone to convert an existing page to StructuredDiscussions, even if the initial page is protected for move.
The goal is to respect the page protection concerning moves. The current state allows anyone to move a page using Structured Discussion conversion.
On MediaWiki.org, we have a talk page sandbox located at https://www.mediawiki.org/wiki/Project_talk:Sandbox. This sandbox is for testing on a wikitext talk page. Our StructuredDiscussions test page is over on https://www.mediawiki.org/wiki/Flow/Sandbox. Despite that the talk page sandbox is protected against moving by anyone who is not a sysop, users are still able to archive the talk page. StructuredDiscussions should respect the protection status on that talk page, or have an option to disable converting to a flowboard for specific pages, as a wikitext talk page sandbox having a flowboard content model defeats its purpose.