They're restricted, it doesn't mean they're letting them go. Rockets did not extend Lowry, but it doesn't mean re-signing him isn't an option.
Brewer is better for the Jazz than Ariza would be. I don't want to say he's a system player but offensively he wouldn't fit with most teams...especially ours. You gotta hit that 3 to play around Yao. With that said, Ronnie Brewer with an outside shot would be one heck of a role player.
Brewer, imo, should always be mentioned in consideration as one of the best wing defenders in the league. Definitely better than Battier and Ariza in my book.