Session Lock Data Script information help

I need help to understand something about session locking script from This tutorial please.
You can see that when player i loaded, the script overwrite data session locking with os.Time(). But this value is never used anywhere after so i don’t understand what it does (the goal of theses lines ?). More Over, it broke the default data and overwrite it so alll the new players that come can’t even load their data. So it seem like that this tutorial have some problem

Here you can see when the player is loaded, if it’s a new player it will overwrite the default SessionLock and broke the game for others new players that join, and i don’t even understand why they overwirte the Session Lock with os.time() since this is overwrite in game regurlary (at each auto save, is it should do i guess). Any help is really apprecied, this broke my datas script