Does everyone else see a 404 page at the archive.org link? That's the same thing you get today when you try to access /index.cfm so I don't see how this is any evidence of Facebook using Coldfusion.
The page contains a "This content is currently unavailable" notice but the fact that it's been archived as index.cfm suggests there was once a Coldfusion page containing content. One complicating factor is that, although I don't know Coldfusion intimately, I understand index.cfm often operates the way index.php does in older PHP frameworks, ie. as the root of a query string for all the routes in the site.
The archive.org entry for 2012 is orange, indicating it was a 404 back when it was archived. There's also archived pages for /index.php that resolve successfully all the way back to 2005. Maybe someone just manually asked archive.org to crawl that URL.
Sorry I could have been clearer. The archive.org page that shows all scans[1] will mark dates as orange (4xx), green (3xx), or blue (presumably 2xx). The reason I don't think that the link you posted is indicative of something is that all the scans of that url resulted in 4xx's. As opposed to scans of index.php[2] which primarly show 2xx responses. Any framework, Coldfusion or not, will generally throw a 404 when you hit paths that don't exist.
But wouldn't an index.cfm have existed at some point for the archive to flag specific years with an entry? It's the archive doing the scanning, not me.