After the awkwardness of last night, Jim was determined to go full steam ahead with a strategy of denial, pretending he hadn't noticed anything between Juno and Marco and that there was definitely nothing to talk about. He should have ignored it in the first place but he could still start now.
And there was a more important crisis to focus on, anyway. He kind of thought that Pam had a point about people needing to commit to the cleaning part first, but he left it alone and just said, "I'll work with Pam on the cleaning. Obnoxious neat freak, it's my thing."