Seemed crystal clear to me.
BB is not concerned about the actual act of drinking Champagne on the summit on some moral or philosophical level, but he is concerned by the reaction of actual policy makers at BSP.
If you accept that BSP policy makers want to maintain a spirit of wildness, and see Baxter Peak as a place where individuals should quietly connect with the majesty of nature, he has a point.
Rember, it not any individual celebration, heavy influx of climbers on a given day, or minor rules violation that would drive the BSP decision makers to make a decision we don't particularly want-- but the cumulative weight of all of them together.
BB is right to be concerned-- Even if this case is like going 56 in 55 mile zone.