Bruce can only assume 'slagging' means kicking his ass into Arkham where he still considers might be a better fit for the strange young man currently standing in the middle of Wayne Manor. Bruce had alerted Alfred, but he was actually away with Dick and Barbara on a mission in Peru. Something that was necessary, even if Bruce was loathe to loan out his closest partner. Alfred had given him some insight, but it wasn't much of anything Bruce hadn't already considered.

"I'll need to see the suit," he says instead of acknowledging anything else.