Oh man, Marco, do not tempt her. Her main argument at this point would LEGIT just be "it won't stick here". (Their red kryptonite-enforced bonding time has made her consider him as something like human for the first time in a long, long time, buuuut that does not want her make to murder him less.)

She is def stalking his convos on the network, so she'd know better than to straight out tell him NO THIS SHIT IS DANGEROUS STOP IT - clearly he's already been through Some Shit and won't react well to being condescended to. So, naturally, her brain goes to "so if he won't stay away and he's got an in with the Joker......"