EEOC's regulations 29 C.F.R. § 1604.11(a) define sexual harassment as "unwelcome . . . verbal or physical conduct of a sexual nature . . . ." The terms heterosexual and homosexual (and gay since it is another term for homosexual) refer to the sex of the individuals having sexual relations. Therefore, the use of either is a sexual comment. Most heterosexuals don't consider being described as heterosexual as offensive. Unfortunately, many homosexuals and gays still consider the descriptions as unwelcome and offensive. If the recipient does, he can allege sexual harassment. Technically, a heterosexual who objects to that term and considers it offensive and unwelcome can allege
sexual harassment.
The inquiry the employer is required to conduct when it receives a complaint of sexual harassment is designed to determine whether the complained of incident occurred and whether the conduct is sufficiently frequent or severe to create a hostile work environment which requires the employer's intervention. The employer's responses to the complaint: not conducting the inquiry; telling the complaining to ignore the comment if he wants to keep his job and not telling the girl that her comments were inappropriate and must, both of which suggest that nothing is wrong with the statement, regardless of the number of times it is said; and then terminating him for raising the issue - if they occurred as the OP says, all violate Title VII.
However, I agree that the OP needs to watch his own language even though he's not talking directly to those he is describing. He adds nothing to his case by saying that the girl is as "dumb as a box of rocks" and referring to someone else as a pedophile.
True, the Simile "Dumb as a box of rocks" may have been harsh, I should have said: "Very lacking in mental aptitude." You do have a point. But hey, I just got fired over this, I was upset when I originally started posting.