[thincom2000]

To check for product updates, it uses a built-in version checking function because the function vBulletin gives doesn't work for the VaultWiki version numbering system. (Some VaultWiki versions have 8 points and vBulletin's version function only supports 5 points).

The version number lookup is considered to be "external content"
This lookup does not load HTML content from any external source, it just asks for the numbers.
The lookup validates the external server against a bundled trust store, so it will never communicate with a different server for example if someone else buys the domain name in 20 years.

You cannot disable that, no. Once per 24 hours it checks if there is a newer version and shows an alert to admins if there is.

If you are really concerned about the "external content" flag, I would compare it to something else: the full version adds support for Facebook Share/Like, bookmarking, etc. These functions are also considered "external content" by how they work.