I don't necessarily disagree with you, but I have a hard time feeling sympathy for anyone who has the means to blow 6k/mo on a luxury rental. At his level of wealth and privilege he's not really a class traitor is he? A bourgeois parasite on other bourgeois parasites maybe, but not a class traitor.
Semi tangent warning. Being a socialist doesn't mean taking a vow of poverty. If you're in a position that affords you a certain level of wealth, that's not an inherently bad thing and you're not "less socialist" for it. There are obviously systemic pressures that act on wealthy people that encourage certain behaviors and that's something to be aware of and mitigated as much as possible. Living in a capitalist economy means we have money, and people with a lot of money can put it to good use in supporting struggles. Until we can rid ourselves of market economies there will always be some people who have more wealth than others, it's a function of currency no matter how it's structured.
I obviously can't say this is the case for serj, I don't know much about his finances or what he does with it outside of supporting left wing movements and the liberation of Armenian people. He may do other things with his wealth that would be unbecoming of a socialist, can't say. But the fact that he's wealthy doesn't immediately mean he's a fraud, the fact that he's a landlord definitely raises some eyebrows. But the elements of violence and coercion that are normally present in housing rentals aren't really present here. If you can afford a 6k rental, you can afford to buy a house basically anywhere. With that kind of budget you're not really in a "fork over most of your money or be homeless" situation. Yes, private property is bad, but that's just an aspect of our current social structure that can't feasibly be eliminated yet. He's playing the game a bit and that can be fairly criticized given his stated political positions, but it's not necessarily an affront to the concept of socialism itself