They may not even know who the hell he is. He's just some schmoozing pleb trying to ingratiate himself with people at the party hoping for an in. Exactly as Sage describes him. Here's the entire conversation with the three men.
Red haired guest: "Come winter, I'm considering taking the family there for a ski trip."
Blonde guest: "Me and the missus rented a cottage a bit further up north. Trust me, it's worth every dollar."
Red haired guest: "Maybe we could have a company retreat there? Tax deductions, wink wink. Hehe."
Sage's dad "Haha! What's this I'm hearing!?"
Red haired guest: "Haha! You didn't hear anything from me."
Sage's dad "Grr! I'm going to report you. Haha!"
Sage's dad "Just kidding! I'm invited, right?"
Blonde guest: "I do like the sound of a company retreat, but perhaps for another year?"
Red haired guest: "Yeah, you're right. This year is too short notice."
Sage's dad "Hah, what a bummer! I'll be back for you two later!"
Sage's dad "Right now... Refreshments!"
Blonde guest: "What do you think about November?"
Red haired guest: "Sounds great! I'll run it past Gina on Monday."
The only other time he chats is with some students.
Can you, like, spell it out for us? Looking at the conversation above, which part makes them "clearly" co-workers?