This is currently not supported but I like the idea. An alternative would be to integrate that functionality with the existing @PageHiding feature. So, basically add support for an optional parameter to @PageHiding lifecycle methods which allows to proceed (or stop) the current transition.
Do you want to create a JIRA for us: https://issues.jboss.org/browse/ERRAI
Of course, you're more than welcome to take a stab at implementing this and us send a pull request!