To be frank, I am in the camp of "Cat5 has no items and he masoned me so he should be clear". This runs with the notion that Scatter itself is an ability rather than an item, and if he Masoned me then he couldn't have used Scatter in tandem.
With Louis' result, I currently feel more comfortable about Cat5 being town although the possibility does remain open that he could have performed the NK as well. My current proposal however is that he cannot have opened the mason with me and scattered in the same night. Someone else must be responsible for the scatter and did it again to Cat5 to keep our suspicions on him.