I think he deserved first team.
agreed - definitely over Luka. JB plays defense and didn't have Lebron and Reaves as second and third bananas. Also didn't have a good season from White to be a quality second banana behind him.
I think the argument for Brown over Luka would be based on games played, but the NBA kind of took that off the table. In the games that Luka played, he is a better player than Brown. More points per game, rebounds, assists, 2P%, and 3P%. I get that defense does matter but Luka can (and did at times) carry a team in a way that Brown can't. I think Brown and Cade Cunningham are closer. Both had great seasons, break out seasons of sorts. That one is a fair debate, could reasonably argue either way on that one.
As to Luka vs. Brown, I would be all for looking at total points, total rebounds, and so on vs per game stats, which would favor the player who played more games (or minutes). But even with that, Luka had more total points, total rebounds, and total assists, even though Luka played 154 fewer total minutes and 7 fewer games.