Lee- Because Ammonia will do some very bad things to steel alloys
take a whiff of any of the copper remover type gun solvents Sweets 7.62
etc, what you're smelling is Ammonia, it's great for breaking down jacket wash in modern rifles, but if used properly it's only left in the barrel for
10 to 15 min. some guys will leave the barrel wet with this stuff overnight and find there barrels frosty clean the frosty appearance is due to microcrystalline stress fractures that barrel is now toast as it'll be a terrible fouler. The amount of ammonia in a given glass cleaner product varies and it's generally not as concentrated as the solvent but why take a chance particularly as steel is somewhat pourous, while your barrel might look nice and shiney when you shine a light down there, if you look in there with a bore scope under magnification it looks like western Afghanistan, plain cold water is suitable for cleaning up afetr BP and
diluted glass cleaner might cut the crud a little faster, but you certainly don't need ammonia.
fredj