I really dislike anything that assumes traditional stereotypes in relationships. It's not like having a wife, it's like having a spouse. You know, that partner in life with whom you share financial resources and household duties and parenting responsibilities. Around here SAHDs aren't that unusual anymore. I get that to some people it's still unusual, and that's where there automatic reaction is "wow it's like a wife" because in their mind there are set gender roles in a household. It's a perfectly understandable reaction as society needs time to shift it's viewpoint. But that doesn't mean it's right. I don't think the guy was blatantly rude, but his comment was sexist regardless.
Imagine if he asked what you did and you said "Oh I'm a lawyer" and got the response of "Wow, just like a man!" clearly, that type of assumption that a role belongs to a specific gender is very outdated and old-fashioned. Most people now except that women can do "man's work", so it should work both ways.