Microsoft has them, K5 units. Plans to weaponize them with tazers and maybe something else later.
If a security robot can use a tazer on a human being, then they can use an AK-47 or AR-15 or anything else like a flame thrower.
Is the robot autonomous? Does that question matter when it aims a weapon at you and fires?
We might have an ED-209 situation here, malfunctioning robot that kills innocents.