I agree that so far this seems the most likely. I think it is targeted in the sense that the killer knew that someone called "Doctor" lived there and targeted them for robbery because he assumed a medical professional would have prescription drugs, plus small valuables like cash and jewelry. Maybe the door was unlocked through a fluke or maybe there is a connection such as the perp being the relative of a cleaning person or dogwalker with access to the code. The perp hopes to surprise them in their bed and hold them up for drugs, then panics or lashes out when they explain they don't have any drugs in the house. In that scenario, the perp might not have actually taken anything at all.
Side note: JMO, but in addition to incorrectly assuming that a medical professional would have drugs, I think a prospective home invasion robber would be wrong about the amount of cash and jewelry at the house of an upper-middle-class person. People like that use banks and safe deposit boxes and might not have a ton of valuables lying around (which could upset a robber). In my area lower-income East and South Asian immigrants have been targeted for home invasions because they are less likely to use banks and they keep their assets at home as cash or gold jewelry.
