Could This Be Deemed 'unlawful Restraint'? (not Ice Related)

Location: Illinois

TL;DR at the end of the post.

There is an adult currently couch surfing while trying to find a better paying job and an apartment.

They currently stay in a home of a friend who has a family with young kids. There is no written agreement or terms for the living arrangement that anyone signed. Just a "friend helping a friend" situation.

One of the children is non-verbal and needs very attentive care and monitoring in order to keep them unharmed. One of the safety measures in the home is now a combination lock on the INSIDE of the front door to keep this child from running outside and into the street. The child running out has happened before and this is the parents' solution to it. Everyone has the code to the lock EXCEPT my friend who is staying there.

Whenever they need to leave for work or anything, they have to text or tell someone else in the house to come and let them out.

While this hasn't inhibited the person from leaving when they need to yet, they realize that in an emergency, if the lock is engaged, there is no way for them to leave the house secure should they need to leave right away, not without someone else who knows the combination is there. This lock is a new security addition and was not there when my friend first starting staying there.

When they installed it, the family never gave them the code, just instruction to let them know when they need to leave the house.

I'm guessing because the person isn't being FORCED to stay inside that it's not imprisonment, but I wouldn't say they have the freedom to leave whenever they want to.

There is much more going on behind the scenes interpersonally that my friend has to deal with, and could get complicated, expensive, and possibly dangerous should all of it be revealed.

TL;DR: Is having a combination lock to the main entrance of a house illegal or unlawful in anyway if you do not provide the combination to it? Edit: This person was never given a key either. So if none of the family is home, they cannot get into the home until they return.