They're explanation of why RM was blocking people was unfairly was "Our system sometimes make mistakes in understanding context and nuances when it assesses which videos to make available in Restricted Mode."
So basically people asked "Why was it doing this" and they responded "because it was doing this"
they don't even provide a complete list of features considered by the algorithms
and more than one of the features they do mention rely heavily on user feedback and creator input (descriptions and tags and such) which are some of the ugliest and most easily corrupted types of data :/
Of course it was going to find patterns in mature content that it shouldn't have found.
It's like releasing a child into a room for the sake of policing behavior