Convincing humanoid androids with enough space for a nuke are most definitely not a current 2012 destructive technology. Walking is still a challenge, let alone any sort of intelligence.

I'm not really clear on what an AI has to do with it though. A remote controlled robot would be easier, cheaper, and more reliable, but even that's unnecessarily complicated. If you wanted to move something heavy through a crowded area without attracting attention, you'd just hide it in any of the common wheeled things we see every day. Like a wheelchair. Or a car. Or a truck. I'm pretty sure terrorists have "Let's put this bomb in a truck" figured out already. The 2010 Times Square guy solved the transportation issue, he just wasn't good at making bombs.

EDIT: More to the point, almost any technology has the potential to be used for purposes that we don't like. The real question is about the people who resort to those tactics, why they choose to, and what means they have access to. The vast majority of the world is against nuking large groups of people, with androids or not. The ones that do don't usually have access to nuclear material, bioweapons, or advanced robotics.

If anything, a "nukedroid," would be the next generation of ICBM, built to avoid missile defense systems. I don't think science fiction's common prediction of widespread androids is realistic, and there are plenty of equally far fetched weapon predictions that would be difficult to defend. What about a nuclear mole-bot that burrows under a city from hundreds of miles away before surfacing and blowing up? Or nanobots designed to infiltrate through a water supply? For the foreseeable future, metal bullets and explosives in conventional cases will be the most economical form of killing people and blowing stuff up.