Interesting idea, but since a confirmation statement must be present on each of the profiles you are confirming back to the MRCA, you will need to copy and paste something on each; so a free-space page actually might result in more work for you. And if the confirmation statements are the last items in the Sources section, they will be at the bottom of the page and seldom seen.
However, if you decide to try it, I hope you will give some thought to a naming convention. Whatever you name the free-space page becomes part of the URL; so, if you create a free-space page named, say, "John Smith DNA Confirmations," no one else can create such a page for a different John Smith using the same page name and URL. At the least, you would need to incorporate the WikiTree ID for the MRCA.
Some things concern me , though, about having all the confirmation details for all the descendants of an MRCA on a free-space page:
* If the free-space page is for an MRCA, say, eight generations back (or much further for yDNA), it eventually could include DNA details for a very large number of descendants. It could be difficult to find the information for the correct testers on the page.
* The free-space page would "belong" to the creator and presumably would vanish if the creator died or canceled his account. I'm not certain how that works but you would need to have more than one profile manager to prevent that.
* If the privacy level were not set to Open, only the PMs could add information to the free-space page, creating another hoop to jump through for other descendants of the MRCA.
If you try this, please let us know where we can see an example.