I see your point, however, if you look back at Yumi's event, you will realize not even "Sensei" has complete control of what he wants or does.
And if you also remember our previous arguments about Chika's fingering event, you will realize that "by simply pursuing X girl's events, you are enabling Sensei to do things to her. You won't be warned about what he will do. No choices will be prompted to choose from"
View attachment 996643
Hence, it doesn't matter how much "must protect" Sensei can get, we don't know how consistent this is. This very world and character was designed with this in mind. To enable those events.