approach to allow a descent to 2600ft (well below a constant-angle path)
Again, you keep repeating this "well below descent path" like a broken record, it is your poor understanding of the approaches. Take any other say ILS approach and any point before the FAF will be for sure "below descent path" by obvious geometry, it is simply false to consider points before FAF as having anything to do with the descent profile. This is how great majority of the approaches in the US are constructed, it has nothing to do with safety. Grab some Canadian charts, you will also find similar examples there. Yes, it is absolutely OK to descend to 2600 at BIDPE and stay at 2600 until you reach the FAF, such interception of glide slope from "below" is perfectly routine.