DFC:
You need to consider what an AIP is. Under ICAO Annex 15 it is a publication " ... containing aeronautical information of a lasting character essential to air navigation" (my emphasis).
Therefore, whilst the AIP will set out the legal position it is not the source of the law, which is the Act. In any case of conflict the Act would always prevail. Simply arguing that you have complied with the AIP will not get you off the hook if you have not complied with the legislation. The relevant legislation here (under which you would be prosecuted!) is the Terrorism Act 2000, as amended.
The AIP is indeed wrong, as it mis-states the current law as contained in the 2000 Act.