Of course, but you're ignoring that protected class status is usually granted when discrimination be so pervasive that it is a burden its recipients.
If it becomes commonplace to discriminate against people based on their political ideology then we may very well see the 'political party' protection broadened.
There are two discussions encapsulated in your comment. One, should political ideology be a protected class? And two, if so, how would you delineate protected "political ideology," something inherently more difficult to observe than ethnicity or sex, from unprotected views?
The same way we deal with sexuality as a protected class, which is to say poorly but better than nothing.
> Should political ideology be a protected class?
I think it should, I wouldn't have said it was necessary in years past but it really seems like we're heading down a road where people are going to have to signal the 'right' political values in order to get hired.
If it becomes commonplace to discriminate against people based on their political ideology then we may very well see the 'political party' protection broadened.