Probably. This seems like a public space so almost certainly. However if this was private space sometimes the rules are different. Once in a while I have to go into our factory (not even once a year, but sometimes), and they always make it clear that forklifts have the right away so watch out. (forklifts have poor visibility, so by giving them the right of way they ensure nobody expects them to stop - in practice a forklift driver will stop if they see you, but this way they are not expected to see something that is impossible to see)
I don't think this shields the company from liability. Instead it provides some ammunition to use in the event of a lawsuit.
Things are very different between employees and the general public. I imagine a jury would find that a lady-busting security robot is negligent by default. Whereas, a fork lift driver would be assumed to be doing his job and that situational negligence would need to be proven.
Note that my company does a lot of mandatory training before you are allowed to enter the manufacturing areas. Forklift safety is only a part of it (though a large part as everything else is common sense says you wouldn't do this while forklifts don't follow common sense rules)
I agree if this is a public place a jury would and should find the robots at fault. (unless the robots are running some sort of arrest her routine, or knocking her over because a bad fall is still better than some other danger)
Seriously. What if this thing bowls into a child and seriously injures them? Or a dog that is confused on what the hell is going on? I'm not even against them for mobile surveillance but they need to be safe.
And if these things are really 400 pounds with a low center of gravity as people are linking below.......well then I guess you will just have to enlist the help of one other friend in order to knock it over to prevent it from hurting anyone else.