Sex to be outlawed for Oklahoma's student workers

Eugene Volokh has posted about a problematic law proposed in Oklahoma defining one type of rape as sex occuring:

Where the victim is an undergraduate student under twenty-one (21) years of age attending any college or university in this state or the victim is attending any public or private secondary school in this state, regardless of the person's age, and engages in sexual intercourse with a person who is an employee of the same college, university or school system unless the two persons were legally married prior to enrollment or employment in such college, university or school. . . . .

Volokh points to the absurdity that is "infantilizing 20-year-olds" (something well taken care of already by drinking laws), to the right of professors to sleep with (of-age) students not taking their classes, and, briefly, to the fact that students are often also employees of their colleges. This last point strikes me as by far the most crucial--even if you don't buy any of that "consenting adults" argument (an argument I happen to buy, but regardless...), how exactly can otherwise legal sex be prohibited between members of two highly overlapping groups? I mean, where else are college students likely to work, other than at their own colleges? (Does this make a sketchy student worker at the Reg who sneaks off into the stacks with a porn magazine a self-rapist?)