Yes, he is correct. Preseason do not count for milestone stats, as they technically aren't stats as the games don't count. You can obviously get weekly XP goals, but no milestones.
During the season, depending on the milestone it may unlock before the end of the season. For instance, in my first CC where I have actually been through an offseason, Cliff Avril got his points for breaking the sack record immediately upon breaking it...
It really just depends, but not in preseason.