This is probably the last I'll say without seeing it for myself, but what exactly are these people offended by? That a slur is used, regardless of context? Even if he said "I won't have a filthy chink in my house.", there probably wouldn't be an issue if it was acknowledged as innapropriate within the context of the film.
If Stiller's character is shocked by the line, it leads me to believe their problem is the flippance with which the double entendre is used, which is true to a point. It's a pretty strained joke. However, they're clearly just busybodies. Things 10,000 times worse were said on The Jeffersons without incident. The Chinese are jealous of the racist action some of their contemporaries receive. Have you seen some of the other things they get upset about? Fuck em.