My office is very flexible. There are people who are in only a couple days a week, some only a couple times a month. All are in contact via phone, email, and IM. No one shakes their hand when they are in. If my boss (who actually lives in another state) is gone for a couple of weeks, no one would shake his hand when he comes in. That would be weird and awkward.
Our consultants and auditors (ie, a more formal relationship) are in and out frequently - no handshake. If we have a meeting with someone we haven't seen in month or so, and it's a formal meeting, then handshake. Even then, if it's an informal meeting if they are people we know pretty well there likely wouldn't be a handshake.
JM and CM were in constant contact, and may not have seen each other daily, but they certainly saw each other frequently. I would be shocked to see two people who worked together closely for years shake hands when they have an informal meeting for lunch wearing shorts at a chic-fil-a.
Of note, I'm in a formal professional office on the east coast. I've also lived for years in southern California in a similar environment. SoCal is much less formal than the east coast. Add to that JM and CM were in a blue collar business, working in a shop fabricating a product, a much less formal environment. I just can't see them shaking hands.
They may have exchanged paperwork, shared fries, something like that. I've never been to a Chick-fil-a, I don't know if they would be handing food to one another. I would think DNA transfer would be less in those cases than with direct skin to skin contact via a handshake.
Just my observations.
