"rocket shaped" is sort of a generous way to describe it.
My first exposure to security robots was actually a company marketing a repurposed remote-controlled lawnmower platform. It was nearly the size of a Smartcar but low to the ground and designed to cross difficult terrain. Even so, a similarly designed lawnmower tumbled down a hill and killed its operator around the same time frame (I don't think from the same company). That all makes the KnightScope design rather surprising, it seems like these things falling over and injuring people is an inevitable liability. But at least my outside perspective is that the companies using these things don't seem to have much of a head for avoiding liability issues as they're often fielded in ways that end up in negative press coverage at least... not even really due to any kind of fault per se but just the user's lack of consideration of the optics of deploying a large, er, rocket-shaped robot to programmatically harass homeless people.
Some might remember the decade-ago jokes about "do not enter elevator with robot" signs and other artifacts of robots coexisting with humans. It sort of feels like the situation hasn't really advanced that much, we're just getting used to it and actively making use of the present inability of robots to coexist in polite society.
Pure speculation on my part, but having it around 5 feet tall is presumably for the optical cameras to have a better view of the majority of adult human faces. If you're talking a remote control car (at least like the one I had as a kid), any camera is either going to get great photos of people's ankles & shins, up their noses if they're close, or lose detail because they'll have to be too far away to get a decent angle to look at a face.
https://www.knightscope.com/