I didn't mean to make it seem like it is a guarantee. https://www.sciencedirect.com/science/article/pii/S1751731116002378
Here is a link
And another:
https://bitchinchickens.com/2022/04/25/keeping-a-bachelor-rooster-flock/
As for all of you discouraging this person from keeping the rooster, and saying chickens aren't indoor pets, you are contributing to roosters being killed or dumped.
I think if you rehome the hen (people will take her) and get another rooster from someone who can't keep it (you will totally find one) you can keep them together indoors. They would like to be able to play outside sometimes (when outdoor and indoor temps are close to indoor temps, and have a...