Because they asked him. It might be an obvious answer but they did ask him how he was enjoying his time with the national team, what was different about it etc. The problem is that his words were twisted really, not that he said them.
Great example is Hummels the other day. Journalist asks him: "rumours link you to Chelsea but they have no CL football whilst BVB do, that's an argument to stay put no?". Hummels says yes, such things definitely do factor into a player's decision to move. Headlines from that? "
German international snubs Chelsea" He did no such thing, all he did was confirm the interviewers assertion that a lack of CL was not ideal. The thing I think many people need to realise is how little regulation there is with press standards when it comes to this sort of interview, and how footballers in particular are not especially savvy. A huge number of things you read them saying will be answers that they have been very neatly lead to, because it makes a great story. You ever wonder why Jose was so popular with the press here? A large part of it was down to the fact that he understood this, and would give journalists the perfect soundbites without them needing to press him. It's no coincidence that they turned on him when he stopped playing along and began to basically ignore the lead questions he would previously indulge.