Yeah that was the only downside I found with Actionable Agile. It didn't answer the question up-front. However, I think it can work if you're able to estimate the number of tickets instead of time frame. So instead of a best/worst case estimate in time, you'd estimate the best/worst case in number of tickets a task will need to be broken up into. I did this one time when I needed to try to get a better understanding of estimation up front when the work wasn't well defined yet.
It's possible that people may give better estimations when thinking about the number of tickets because then you immediately have to think about the number of individual components whereas with time, you're going more by feeling.