That's likely just the case for the ACRO plate. If you look at their website they had to do some engineering to fit a BUIS behind the ACRO. The AOS gen 1 ACRO plate looks the same. Their other plates accommodate front and rear plate-mounted BUIS for most popular dot sights.
http://www.agencyarms.com/aos-plates
I just hope this new one is as low or lower than the gen 1!