It is not. The Saints were still scheduling interviews when McCarthy became available 2 weeks ago. It very well could be that once MM became available, the decision was made MM was the preferred candidate.
Or the whole thing was orchestrated this entire time since early January for MM to maneuver his way back down here. I wish I could find the article but there was a story in early January where a source was indicating that the Saints and McCarthy were in play and that MM was trying to backdoor his way down here.