Bullet,that is the way they work. If he complained about it, and raised his suspicions, then yes, he would have got pasted. Not quite as much as he would have as he would have as PM granted, but his ambitions, when Chancellor, were well documented in the broadsheets
Plus, RB was furious when he briefed the the Press Association which of course stopped the 'exclusive', and said that (to paraphrase, will find the guardian article if you want) 'this was not the way it works and if you want to be PM then you'd better fall in line'
Now Brown, like most politicians. was not adverse to playing politics in normal, well politics. But the Murdoch press knew this well, and eventually did paste him. He helped them along the way of course, but there is no doubt that political reputations can be seriously damaged on a press baron's/editor's whims. This is why they court them. And why also why shoudn't