Probably, but I just checked the recent MLB additions and Chad Fairchild started in the Gulf Coast, so it's not where you start, it is where you finish. You have to figure out how to get there, just like they all did.
For a current AAA Umpire the progression was as follows:
2006 GCL
2006 NYP
2007 SAL
2008 FSL
2009 FSL
2010 SL
2011 SL
2012 IL
Many of the Umpires currently working the Arizona Fall League were working in long-season A-Ball in their 2nd season. If I remember correctly the Rookie League Umpires are in a seprate group from Short-Season Umpires when the end of season rankings comeout so if you spent the whole season in Rookie Ball you would move up to Short Season A-Ball so your assumption appears correct.