That's pretty bad. Interviewing should also be about selling the candidate on the company. If they get an offer you want them to accept. If they don't then you don't want them bad mouthing you to other potential candidates.
If an interviewer insulted me or my language choice in an interview it would definitely make me wonder how they would treat me as a coworker.
The entire Google interview process is slanted that way. They keep making you feel privileged for being able to take that interview, and almost never try to make you sell the company to you.
This has changed a lot for the better in recent years.
Also, a lot of geniuses are socially inept. I doubt you said everything right in your interview either. It helps to smile and keep going when one person in ten shows a flaw.
If an interviewer insulted me or my language choice in an interview it would definitely make me wonder how they would treat me as a coworker.