The minimum setting in VBulletin is 20 seconds and that is the current setting.
The idea of the autosave is to auto save a message being typed in case of a browser crash etc. Members did say that 60 seconds would be too long. In your message your are referring to a specific case with a touch sensitive screen on a Vista system so your comment does not seem to be objective but rather subjective and specific to a particular piece of hardware and a particular operating system.