This is a reference to the episode "Helpless" (3.12), in which Buffy comes face to face with a truly shocking abuse of trust by Giles. It doesn't help that he has betrayed her trust only at the instruction of the council of watchers, his employer and supposed "governing body."
I think what moves Giles into non-toxic territory, in "Helpless", is his reaction when he realizes the enormity of what he's done:
- He realizes he has done wrong, and is filled with shame.
- He admits his mistake and tells Buffy everything.
- He apologizes -- and more importantly seeks to make things right: "You have to listen to me. Because I have told you this, the test is invalidated. You'll be safe, I promise. Whatever I have to do, to deal with Kralik and to win back your trust-"
- He follows through on this promise. He stands up to Travers and the council, taking Buffy's side, entering the field of danger and disobeying orders to help her. (She still dispatches Kralik, of course, but a secondary baddie takes her by surprise and Giles manages to dust him while Buffy looks around for a weapon.)
- And so Giles makes things right with Buffy at some personal cost, since he is fired for it.
Surely this is non-toxic masculinity. He's an authority figure for her, an unambiguous father-figure. But when he messes up big-time, he is frank and contrite and sets aside his own safety and security to put things right. There's no "father knows best" mentality here; he owns his mistakes.