Cat advice please

Theres an outside cat that “lives” a few houses down from me. This cat has no tail and all it has no meat on its bones. I could feel this cats rib cage the entire way down. The cats stomach past its ribs was caved in, even less there then the ribs. I grabbed 2 cans of food and a container filled with fresh cold water. As im feeding it its “owner” comes out and immediately starts screaming at me to get away from his cat cussing me out then grabbing the cat and running inside with it. This cat has clearly not eaten in weeks. It has a collar but no tags w address. The poor baby was the sweetest thing to. Immediately comes up bunts my leg and hand then starts purring soon as i start petting it. I want to coax the cat to my house and let it live as an outside cat where he knows he can get food and water from me whenever it needs. (I currently have 4 indoor cats ive had all since babies) I worry if i call the cops for animal abuse, which this waste of air deserves, but i worry the cat will go to a shelter and probably end up being put down eventually. If i coax the cat to my house would i face legal troubles if that sack of shit called the cops? The cat is clearly not being cared for and malnourished. What should i do? I refuse to stand by and let an innocent animal be abused and neglected. I am more then happy to put out food and water every morning for the poor baby. The owners excuse was its old as to why its ribs were showing and hasent eaten in weeks. Any advice please? My hot headed side wanted to react violently to this scum for the condition the cat was in but i stopped myself. I need to know this poor baby is safe