Assalamualaikum - my mum’s Muslim housemate won’t respect my hijab

Assalamualaikum sisters, I need to share this because I am honestly baffled and not sure what to do. I’m a 28-year-old revert, raised by a single Catholic mum in a mostly Christian country. After my sibling and I moved out, my mum has been renting rooms to exchange students and young adults working or studying here. Tenants have been both men and women, staying usually 1–4 years. Overall things were fine until now. There’s this new housemate I’ll call S. He moved in summer 2024. He’s from a country with a large Muslim population and he identifies as Muslim. He’s a bit older than me and my husband and works in medicine. When we visit my mum - usually around Christmas and New Year to spend family time and for her to see her grandchild - we sleep in a room and use the shared living area on the other floor. We’d always agreed that when I visit it’s okay for me to be in the living area without my hijab, but if someone from the other floor wants to come up they announce themselves briefly and I cover. I keep my scarf around my neck so it literally takes two seconds to put it on. This was never a problem with previous tenants. With S it became an issue. Several times he showed up unannounced and I didn’t have time to cover my hair. At first we assumed it was accidental and we politely reminded him; he said no problem. But it kept happening. My husband understandably got angry and I tried not to make a scene, so I just kept my hijab on the whole visit to avoid conflict. After we left my mum spoke to S and he got upset, insisting the shared space is his just as much and he can move freely. That struck us as odd, especially since his mother and sisters wear hijab. Recently my mum brought it up again to make us comfortable and he doubled down - refused to accommodate us and was rude about it. I’m really hurt to see this from a brother and I don’t know how to handle it. It doesn’t seem like an unreasonable request - I’m visiting maybe 10 days a year and we’re only asking for basic respect in shared areas. Even outside religion, people should be considerate in common spaces - you wouldn’t insist on being unclothed in a shared kitchen just because it’s yours too. Any advice or thoughts on how to approach this? JazakAllah khair.