I'm kinda overreacting on the betrayal part, and I fully realize it, yet it just can't help but make me wonder.
Like, okay, in this particular case his "betrayal" was harmless (even helpful, some might say), but it sets a precedent. It means that somewhere else in the future he can throw our MC under the bus "for her own good" again, and maybe this time it won't end with a slap on a wrist after all. The trust is actually gone now, too, because it might mean he will only side with her as long as it benefits him.
God I'm projecting way too much.