If you speak your mind too freely you rub some people the wrong way, and the ones who agree with you (in this case BM/Germany fans) will adore you for that because they agree with you (you being Muller), but all the others that sympathize with the ones you mock or tease (messi being just an example) will be irritated or even worst, really affected, that's just inevitable.
I for one was heartbroken when Messi didn't win the world cup, I can't control that, I wanted it so bad for the little guy, those comments (true or not, that's not the point, knowing him it's something he could say/do) from Muller really hurt me as they came on top on an open wound, yet, all germans will find it very funny or amusing because he's on their side.
The problem is, Muller himself can handle the heat and probably don't care at all, that's how he is, but people that are fan of his, like you guys, come and DEMAND, that the other people that were hurt by his comments or behaviour respect him, and DO NOT speak their minds freely about him.
So from where I stand, if you like his mocking and him running his big mouth, be ok with our big mouths running against him when we felt like shit for something he said/did.
That's all.