Well, kinda. A RIPA s.49 notice can be defeated with s.53 defenses.
Some people have failed to pass the test of "reasonable doubt" for s.53 (3) / (4) defenses e.g. ( http://www.alphr.com/news/361693/teenager-jailed-for-refusin... ) but in other cases they have succeeded (e.g. Lauri Love had his hdd's taken and the NCA couldn't decrypt them but had to release him on bail; http://www.bbc.co.uk/news/uk-england-suffolk-31544346 and subsequently returned some of the storage (before arresting him again))
There are also people out there working to help the reasonable doubt argument; https://brasshorncommunications.uk/projects/s53/