It’s imperative for the club that Wenger keeps churning our the title challengers line.
We have to remember that the people that go to games, the fans around the area and the country are not the only fans. The club has followers from all around the world and it would be a PR disaster for a club like ours to admit we are not aiming for the title.
For the record, having a target of being champions isn’t the same as having it as your only objective. When Wenger says stuff like this, it’s just to keep the mantra going that a club like ours should be aiming for no less but at the same time we have to be realistic that it’s currently beyond our means - you literally cannot argue that when other clubs have endless pots of money.
Going back to what @Cristo said regarding a statement - that would be a PR nightmare for the club. Despite it being largely true, the club would literally be opening up the floodgates for the media to have a field day. Wenger’s wage and job would come into (more) question, the ticket prices would become a major issue - the club wouldn’t be able to justify the prices if the aim wasn’t the title. The media in general would have a field day and attack from every angle the moment we showed any weakness.
So yeah, even though it’s blatently not true, we have to make it out like we are always aiming for the title.