Your first days are peaceful, for everyone
New players cannot be attacked while they find their feet — and cannot attack either. Plus vacation mode, for the weeks you are not there.
The setting had been in the game since the first day and nothing ever read it. A strong neighbour could encircle somebody who had joined the night before, and the protection we had promised existed only in a config file.
It works both ways
Your first days in a galaxy are peaceful. Nobody can attack, spy on or take ground from you — and you cannot do any of it either.
The symmetry is the point. A shield that only blocks what comes in turns every new account into a free raider, and the usual patch for that (“you lose protection the moment you attack”) is a rule nobody can see until it bites them. One sentence covers this one: for your first days, everybody leaves everybody alone.
It costs something real, and it is worth naming: a newcomer who wants a fight has to wait. So there is a way out — you can waive the shield early, and that choice is one-way. A shield you could raise again the moment a fleet appeared would be a panic button, not protection.
The clock is counted per galaxy. The same person joining a second universe is a beginner there too. And none of this touches PvE or trade: pirates and commerce never cared who was new.
Vacation mode
For when you are away for longer than a weekend. Your worlds cannot be attacked while it is on.
The catch, and the reason it is safe to exist: production stops too. A player who could grow while untouchable would have no reason to log in ever again. There is a minimum stay, enforced on the way out rather than on the way in — checked on entry it would be a promise, checked on exit it is a cost, and that is what stops vacation mode from becoming a one-hour shield in the middle of a war.
Ask for longer than the maximum and you get the maximum rather than an error. Asking for a year plainly means “as long as you will let me”.