The Americans with Disabilities Act does not require an employer to guess and play detective.
Title VII does not (yet) specifically identify 'sexual orientation' as a protected class.
The EEOC, which is an agency of limited financial resources, is going to go after that which will provide the most bang for its buck.
The president made an executive order prohibiting discrimination based on sexual orientation and gender identity last year.
The guidance memo is a necessary read for all employers.
Some companies, worried about employee engagement, are taking a novel approach: mandating a minimum number of paid days off.