Not true.
A woman was expelled from college when it was discovered that she used the N-word at age 15 (innocently mimicking rappers).
White teen pushed out of college after video of her saying N-word at 15 resurfaces
So yeah, colleges do expel students for off-campus behavior they disapprove of.
In West Virginia in the 1970’s at one of the community colleges a student who had lost an arm in the Viet Nam War (at the shoulder so not much use of an artificial limb then) duked one of several male student’s calling him a Nazi and baby killer hard enough to knock the man out cold. The vet was brought up on violating school code after the city cops refused to press charges. He got off with a stiff warning. The female dean of students stood and said she opposed the finding and that she had opposed Viet Vers being allowed to register in the first place as they were war criminals, murderers and narcotic addicts who should not be allowed on a college campus.