Should homosexuality be a protected class?
Do you agree that sexual orientation should be included as a protected class
The OP asks two different questions really. Protected classes are usually "neutral" except for a few select ones such as age (40 or over generally protected from discrimination - it doesn't go the other way (i.e., you can discriminate against young people)).
The law doesn't say - don't discriminate against "blacks" or "women" or "hindus" or "mexicans." It says don't discriminate on the basis of race/color (e.g., black OR white), gender (female OR male), religion (e.g. hindu OR christian), national origin (american OR mexican).
The same goes for sexual orientation laws (in jurisdictions that have them). They are written neutrally - no discrimination based on a person's sexual orientation (straight, gay, or bi).
Now in practice people may find that these laws are not APPLIED neutrally (as evidenced by many people's surprise that a white male is clearly a member of multiple protected classes just like a black female), but that is the way they are written.