The "six players in a class" rule applies to human coaches who are recruiting/signing players. Sim-coached teams are not bound by this and, through a variety of reasons, can wind up with "superclasses" of 7+ players in the same class year. If a human then picks up this team (like you did with yours), that human will appear to have recruited more than six players in a given class.
Now the bad news -- you did not have to cut a sophomore to get from 7 down to 6. You would have been allowed to keep the 7 sophs through their graduation. After their senior year, when you had 7 scholarships to fill, you would have been able to sign only 6 freshmen for the next year...the seventh scholarship would have had to go to a JUCO or non-freshman transfer player.