Total activity, moon coins, and whether you claim froggy rewards or not got very little to do with one another. Doing hotspring, for examples gives activity points but doesn't give any moon coins. Activities that actually gives moon or sun coins are specifically marked with a red/white circle in the background. What he was talking about is you failing to finish those specific events/activity, it has nothing to do with your total daily activity points or froggy.

Piece of advice, though, if you want to make sure to get max moon coins without any of your moon coins turning to mysterious stones, either do decisive bonds at least once every 2 days, or spread your TIs out instead of finishing them all by Thursday (this is only needed during non-3v3 weeks). Also, if you hit either cap during the week, don't claim more of them from mail. By doing this, I usually save up 5k8 sun coins and ~5k moon coins to claim first thing on Monday morning. Usually, by Monday night or Tuesday morning, I would have renewed both sun scrolls and moon scrolls power.