Ben,
Nothing to decipher. Glock recommends against using lead bullets in their polygonally rifled barrels because it can (I said CAN) lead to lead deposits accumulating to raise pressures to dangerous levels.
The situation there is apples to your shotgun ammo oranges.
Unplated lead shot was the norm for over 300 years in shotguns, it causes no harm to the bore unless you shoot enough without cleaning to build up outrageous deposits. You won't do that.
Plating was developed, along with hardening, to reduce pellet deformation as they travel down the unrifled shotgun bore, and that's to hold tighter patterns. Secondarily, hardened shot may penetrate slightly farther.
It's not a safety matter, shoot plated or unplated 00 buck through your shotgun all day long if you want to. You may get more lead & carbon deposits with unplated, but it's no big deal.
Totally different proposition to shoot lead bullets through the rifled Glock barrel and unplated lead shot through a smoothbore shotgun barrel.
Denis