I must admit to being at a loss to fathom out why you have posted this. I don't think that I have ever encountered any hostility to folk who speak more than one language, as I do. I am sure that what you quote is right if you say so, regarding the research. And doubtless your wife's experience...
I don't think you and your wife are the people who were being talked about, as I am sure that deep down you know. The comment was made to try and break down barriers which are there when immigrants make no effort to learn German and thus are more likely to lead separate lives, missing out on...