Considering that i wound up skipping the quarantine, this was done mainly because there would need to have been a pathogen exchange somewhere down the line that the two groups would need to overcome anyways.
The purchased discus were all from a reputable breeder, healthy, and active in the rack systems at Uncle Sam's and have been there for weeks so anything else that could attack them would have to come from my own group of fish and vice versa.
With the tank being bare bottom, housing nothing but the discus and some cardinal tetras which could be moved to a smaller tank if needed for aggressive treatment... it would be safer and convenient to mix both groups immediately, up the water changes for about 2 weeks to allow them to better adjust to anything that the other fish might be carrying and treat anything that comes up if the fish are unable to get over it themselves.