Why is the infinite ammo cartridge that Nemmy 7 drops banned?

I'm asking for information, because it doesn't seem to make sense to me. This is not a cheat or a code that has to be entered into the game, or any time of modification. This is a legitimate drop that the game lets you use after Nemesis falls. Granted, at that point in the game, it wouldn't save that much time, but again, there appears to be no reason that this item has been banned since it is a naturally occurring drop.

If it was a code or glitch, I wouldn't question it but since it isn't, can someone explain this to me?

I dont know if this is a reason, but nemesis only drops the infinite ammo on NG+ runs. On NG runs, he drops the assault rifle. On pc version every run is NG+, but we play as a "NG" by not using any NG+ item. The reason for this is to get rid of the manual books.

There's no reasoning for it, it's a completely arbitrary ruling. And the less time it can potentially save, the more unnecessary this ruling is, from the top of my head I don't see it saving even 5 seconds.