Think of it this way: Is it an abuse of power for a TSA agent to be flippant about his authority to grope you, because you have very little recourse to change that authority or get him fired?
It is not his job to be prejudiced about the company as a whole, to conduct arbitrary investigations, or to punish the company by interfering with the work of its executive team.
The easiest way to do this would be to periodically interview those responsible for implementing compliance. The alternative would be for him to audit (i.e., investigate) Apple's relevant business and operational activities, which would cause a significantly greater disruption to the business.
Bromwich's job is not to passively monitor the kinds of deals Apple enters into. Instead, the court ordered Bromwich to help restructure Apple's internal antitrust policies. Like any major internal policies, they are promulgated and implemented by the high level executives. That's why those interviews are necessary.