Is it correct that some people are ALSO charged on the same day as the knock & arrest?

My ex/children's father said the inital images he was arrested for were subsequently checked on the same day as the knock/arrest and deemed to be "actually not illegal" and that this is "WHY he wasn''t charged with anything" on the day of the knock/arrest. Then blased it off saying so now as part of their whole process they just need check his other devices, and saying this is the annoying part for him because there's a big backlog....

I later saw part of the police report that said those same initial images he'd said were "not illegal" were actually "known IIOC" .. so is there likely ANY truth in his claim of him saying they aren't illegal and that's WHY he wasn't charged on the knock day?!