The Arsenal Load dialog will grey out list items when the item has a different "Binoculars" than the current character's "Binoculars". The code is checking the player's primary, secondary and launcher weapons plus their "Binoculars", but against a list that doesn't include the Arsenal's known "Binoculars". Because the player's "Binoculars" are included in the list of permitted weapons, if the player already has the "Binoculars" that the loadout proscribes, the loadout is bolded (not greyed).
This takes place in the "showTemplates" section of BIS_fnc_arsenal, though the bug is in the GETVIRTUALCARGO macro.
The code that makes the actual checks should be rewritten. It's very inefficient when an Arsenal's gear is restricted.