And that would be one way in which the killer came up with to enter the apartment. If the killer knew there were no cameras on the floors above the first (I believe I've heard that in at least one YT video) then they could drop the mask and hood before knocking. This scenario would seem to reinforce the theory that Scott knew his killer.
That this happened in the middle of the day during the week is something I've found to be critical. It has been explained that Scott was home on Friday because he took a day off from work to extend the MLK three day weekend. So that raises two questions, at least, for me. One, for this person to show up at noon on a day that Scott took off, how did the killer know he would be home? Two, how did the killer know his sister or girl friend would not be there? Well, a person that Scott is expecting might answer both questions. If a meet up is planned by the killer for Saturday or any other time over the weekend and Scott says he will be home on Friday the killer simply asks if he could be there that day instead.
That, in turn raises other questions. How did the killer make contact with Scott? Phone or text or email? Hopefully, LE has checked his phone records. Of course, it could be a face to face request with no phone or email contact. How would the killer be sure that Scott would not mention it to his girl friend or sister or both? I don't have an answer for that one. Apparently this guy did not use drugs of any kind so I believe the ruse of a drug buy is very low if it existed at all. He could have been buying something from the killer as a surprise for GF, sister or parent, but he likely would have said something to one of the other non-recipients. Of course, the killer could have shown up unannounced with the ruse of 'Hey, remember what we talked about...well, I was in the area and .....'.
All of this, to me, seems to give further credence that this murder was premeditated. IOW, I don't believe this killer showed up with one non-lethal purpose and it got out of hand. He (OR she) knew when they started out that murder was the intended result.