Doesn't matter. It's still a silly thing to say. What does posing in underwear has to do with football activities and Ballon D'or. And it's not only about CR ...If you have nothing good to say, don't say anything at all!
What you have to understand is that no footballer is usually ringing the doorbells of certain journalists at saturday evening with Pizza and beer to tell them what they have on their mind.
Every interviewer will try to ask questions which could lead to a response that can make a headline of their articles and that grabbs attention, in either a positive or negative way. Footballers are usually trained to avoid that and give boring, useless standard phrases. The interviewers on the other side will try to get the player relaxed and win his trust, so that he feels comfortable and that way some unconventional response will slip out accidentally, because they start to act more like their natural selves.
The interview was about the Ballon D'Or and therfor him competing with Ronaldo for it. The interviewer asked wether he would do some sort of promotion off the pitch to get recognition, Neuer forgot himself a bit and joked about him not doing underwear ads, because hes no brand ambassador, without any sort of offensive meaning. Unlike Ronaldo or Messi hes not used to that whole attention, the two know already that every word will be used against them thats why they hardly talk about other players or teams even in a positive way. Neuer took it to easy and it was still no drama what he said. In all honesty, I think this is completely irrelevant and not worth a debate about class or whatever.