My opinion of the above highlighted sentence is that it's not graphic. That's the reader in me speaking.
The moderator in me would be happiest if there was a Rape tag on the story if it goes beyond that mere mention of an act that did not exactly occur. Rape is a trigger issue that can greatly upset readers who encounter it unprepared.
Unless there was sexual content beyond that mention of a contemplated assault on a twelve year old, I would not ask for a Minor1 tag on the story. However, again, if there was any consummation of that bad act with an underage individual, we do have to have either Minor1 or Minor2 as story codes, which you do already, so no complaints there,