Been blowing down the barrel since the late '60's with no ill results, nor have I seen anyone injured by blowing down the barrel, in all that time...and I have seen it all.
I have seen a load whoosh as a powder charge was dropped into the bore, but never a problem with blowing down the barrel.
Every safety talk I have ever heard tells us that we should not load directly from the horn or flask, using only a measure to pour powder into the bore. The reason given is to prevent the horn from blowing up from any spark remaining in the bore.
IMHO, a spark remaining in the breech creates a MUCH higher chance of AD than blowing down the bore.
I suggest that those folks who do not want the muzzle pointing at your body parts, for any reason, should not shoot ML guns. There is absolutely no way that anyone can load a MLr without exposing some body part to the muzzle.
As always, common sense MUST prevail over rules and regulations inflicted by paranoid regulators.
God bless
