Reading it, I haven't noticed really anything in terms of offensive content. There's the occasional "Omigod" or "hell", but that's it. Storywise, there seems to be no difference with Classic Archie (except for the stories being longer, but even Classic Archie was doing some of that in its last few years).

Probably a preemptive measure for possible future content.

They probably want to keep the door open and changing the age rating issue to issue isn't smart.