Flint, I don't know if I'm the Mike you were asking, but I don't, and never have, worked for McDonald's. And, aside from the Military, this is the first time I've heard of this type of policy.
Where I work, groups of employees and their bosses get together for lunches and major employee events (birthdays, wedding/baby showers, etc.) all the time. And a Halloween costume contest will happen Friday morning (No plans to participate.). I know of at least 2 married couples even who work at my employer, although each spouse is in a different department.
Reading Julie's and Shaun's postings, segregation of employee and management does not sound like a widespread practice in the fast food industry. Several McD employees who are positive about their store have mentioned special get-togethers, as I remember. It's possible that this for some reason is a policy unique to McD Canada.
As for policies against managers working alongside the crew in certain stores, my question would be, is it that, or is that particular manager is just excusing himself because he's lazy and wants to play the big shot? I've seen both types of manager as a fast food [junkie] customer. Example: There is a Hurst, TX McD's (for you locals, it's on Grapevine Hwy near Colleyville border) where I've seen the manager right there with the crew, he looks between 45 and 50-ish, in the kitchen. That same guy has also taken my order a coupla times at the register. Then there is the Bedford, TX BK (corner of Cheek-Sparger and Hwy 121) which I don't recall for the past 18 months seeing more than one register open, regardless of customer volume. The last 2 times I was there, I saw two managers (separate visits) that didn't look to be very busy. One of them did a token handing out of to-go counter order, and a handing out of my dine-in tray, but mainly seemed to just stand around with a hey-lookit-Ima-big-shot look on his face. Another manager on the second recent visit didn't seem to work very hard either. Sometimes he'd be visible at the front, or [so it appears] he would be in the back farting around. When the new cashier trainee taking my order needed to correct it, she had no problem getting him immediately from the back (ie he couldn't have been that busy). He kind of chastised her for having too many voided receipts (not severe, but he didn't sound pleased), but getting to the point he could have fired up that much-needed idle register, ...and been right there to assist her when needed. Perhaps there wouldn't have been so many errors. Julie, are you sure you couldn't use a change of scenery? How about you, Shaun?
In closing, I don't believe a "natural enemies" thing is as widespread in food service as many seem to think, such as Qx and Base727.