This is not a language problem.

The hotel employee behaved strangely -- as the guests' visitors are not staying at the hotel and just visiting with guests staying at the hotel, the hotel should not have demanded to take the passports of the guests' visitors. That taking of passports is a procedure applicable for guests who are sleeping at the hotel and not guests just over for a chat.

The hotel employee probably had a few incidents where guests tried to "sneak in" other guests to sleep over and now presumes others are doing the same.