Other people have already said it, but - yeah, I'm pretty sure this is Gargan losing his mind due to the symbiote's influence. That's always been one of his main characteristics, really - he was this poor schlub of a P.I who got hoodwinked into being a supervillain for the promise of a little extra cash. He's always had more muscles than brains or willpower - it's hardly surprising that being the host of a crazy brain-starved alien bodystocking is proving deleterious to his mental well-being.