Crossbow specifically states ranged attack power. So the rogue failed to read it properly at that point or was trolling.
Gear wise if it just says attack power it is both melee and ranged. If it specifically says melee or ranged though it is exclusively that. Buffs usually specifically melee attack power now or just attack power. It isnt 100% on everything though in terms of buffs.
The Xbow is actually very strong for rogues in pvp as it is a slow speed high weapon damage. But it does come at the cost of their melee hits being a little weaker due to the stats only effecting ranged damage. If a rogue is more so focusing on their new ranged runes to say, kite other melee so they cant be hit back, its effective. But its more of a meme way to fight in most cases.