Specifically it says
give the person carrying out the examination or test all such assistance as that person may reasonably require for carrying it out.
A person is guilty of an offence if he—
(a)intentionally obstructs a person in the exercise of any power conferred on that person by virtue of a warrant under this section; or
(b)without reasonable excuse, fails to give any assistance that he is under a duty to give by virtue of subsection (7).
So say you have a locked mobile phone on you that requires a passcode to unlock. Such devices can receive broadcasts that require a TV licence, e.g. via iPlayer. Do you have to unlock it?
Would, for example, the argument that your phone or computer contains sensitive or personal data be a "reasonable excuse"? Such data could include embarrassing photos, other people's personal data and the like. In particular I can imagine they may want to view your browser history to see if you have visited iplayer.com.