You wouldn't would you

He had every right to expect privacy. He was in his own living space, with the door locked. What he does with his bike IN PRIVATE is his business, surely ? . . . They had no real reason to use the pass key, and once they did, they got a shock, saw something albeit weird and somewhat bemusing, they should have (no pun intended), beat a hasty retreat !

Norf of the boarder laws huh ?! Are they such prudes up there ? Or is there something more here than is being reported in the article ???

Sex offenders registrar for playing with his bike in his own bedroom? Really? Is that what we have to be protected from?

Weird yes, but dangerous? Great to know taxpayers money is being wasted on nonsense like this....

Was the bike being held against it's will or being asked to do something it wasn't comfortable with. I really think you need the bikes side of the story to make an informed decision but as far as I'm Concerned as long as there is a consenting adult (and bike) then where's the harm. 
Unless he was videoing it to make some dodgy low budget adult version of TT3D Closer To The Edge

Wasn't aware it was an illegal activity.

How was it a breach of the peace? In his own bedroom?

Bizarre.

Apparently there's more to it than the over-simplified, sensationalising press have reported (who'd have guessed?!).  It seems that maybe he was waiting for them to 'discover' him, that the bicycle was largely irrelevant and that some kind of affray took place subsequently.