In my time at Philmont, I don’t remember really interacting with other groups during our time there. Occasionally, activities were combined, but I presume they could keep them separate.
I don’t remember a mess hall, but I guess there was one, I just remember our daily cooking of our food we packed with us on the trail.
But i don’t care anymore what the scouts do, it does seem a shame that instead of getting out in the wilderness where there is no chance of getting the virus, these inner city kids will now be stuck in crowded streets and basketball courts, much more likely to spread disease.
I had the good fortune of going to Philmont twice, the first time in 1976 as a scout, and the second in 2013 as an adult leader with my daughters venture crew. Both times were amazing and memorable. Its a shame, social distancing should not even be an issue in a wilderness so vast.
The mess hall is at the central camp and is used by groups on the In-processing day before hitting the trail and then after coming off the trail before they depart for home. I was one of the adults from our troop who took boys on a Philmont backpacking trip in 1995, one of whom was my son. My son returned to Philmont in 1997 and 1998. As you note, once on the trail, it’s all about using the issued backpacking foods to cook and feed your trail group. Of course, this also means keeping a clean camp to keep the bears out of camp.
Our interactions with other groups was at trail camps with organized Backwoods activities like fishing, gold-panning, mountaineering, etc.