Presumably the coworkers want to hug him or her but they don't want to be hugged.
I've never been in a position to have to turn down a coworker's hug (thankfully), it seems very odd indeed. Like the GP, I woudln't engage in that sort of physical contact with coworkers.
Some people lean toward the hug as a greeting or farewell, especially women. As a woman who doesn't like hugs, it's very uncomfortable for me. I used to work at an agency, and sometimes we'd even end up hugging clients after a big meeting.
I've worked in such places. Kissing on cheek etc is also a thing. It will be interesting to see where that leads in the long tail of the #metoo change. I've already seen a lot of people who I've known to overly hug and show affection at work stop doing so. At one workplace HR got all "scorched earth" policy and made it very clear it wasn't acceptable at all. Apparently the concern was women initiating contact then feeling uncomfortable later and complaining about the person they hugged. Two instances at that site alone. I wonder how frequent it is since I'd never heard of it as a thing before.
