Try establishing a scholarship fund for heterosexuals-only, and watch what happens.
Nope, not legally, If you wish to endow a scholarship at a college, you can attach whatever conditions to it you want. There are thousands of totally weird scholarships available out there: for the left-handed, redheads, being a certain height, on and on.
Of course, the college can reject your scholarship if it doesn't like your demands. And yeah, there ought to be a law that says if a college allows people to set up scholarships with qualifications, they must accept all such offers regardless of what the qualifications are.