When I was police and an RP was going on I would attend. If someone was breaking a rule I jailed them for 10 rocks to get them away so they wouldn't return untill the event was over with.
Scammers should be jailed no matter what. We had a conflict when 2k1 was gold about a KT member scamming a Police member and noone believed the Police and the Policeman was on tag. They hid behind the excuse 'It was RPing' or some bull****. Scamming is ok if it's Kingdom against kingdom... but not kingdom against players.
But yeah... overall rules overwrite RP rules (except in some cases) and the police should be able to interupt RP events.
BUT if it's something like, 'Oh King Hubba of (Malenth) PKed me and he's in the middle of a big RP event where he conquers the world... I should jail him now', then it should wait untill after the RP event is over or like if he was proved scamming. But if Hubba hacked then it should be immediate.