Key thing about avoiding lawsuits is not lack of communication but not having illegal hiring practices. And it’s not like everyone gets rejected for being a bad candidate, you might just have too many applicants and want to stay on good terms with them, maybe a position will open in the future.

And, regardless any of that, a simple but polite, standardised “We closed the position, you didn’t make the cut, we wish you the best of luck” to tell people that they can stop waiting and consider the application failed, look somewhere else, is really never too much to ask. Even if they had to be escorted out by police. It’s ghosting which really grinds my gears.