Okay so I have another theory about what could have happened to him and I am sorry in advance bc this is hard to type out. It slipped my mind about him being sick for two weeks. I can't believe I forgot about that. I apologize in advance if this hard to read.
Paddleboarder speficailly made it a note a few threads ago to point out that Lucas been extremely ill for the two weeks before he went missing. Infact she stressed on this big time. I wonder if by Friday afternoon he was so sick that he wasn't physically able to leave his bed .EG knew that he was nearing his death so she smoked bowls of weed to calm her nerves, got the munchies from it, and just left him there in bed when she and the 1 year old went to Olive Garden. If it was indeed the landlord who stopped by that evening then they'd have searched the whole house for that cat. The landlord or whoever stopped by sees him in his bed (or where ever he was at), assumed that he was just sleeping, and then left. Then later in the dark evening hours-morning hours of Saturday Lucas passes away and EG immediately disposed of the body. This could explain why Lucas was in a pull up also. He would have not been able to go on the bathroom on his own so she was putting pull ups on him. IDK
ETA: Grabbed this from another thread to go along with my theory above. This is where Paddleboarder stressed about him being really sick.