Thomas is a professional basketball player and a very good one at that skill wise, but due to his size, he won't ever be a great starting guard. He has openly complained about coming off the bench though and so us trading for him to bench him behind Smart and AB probably wouldn't sit too well with him. I totally get his mindset, because if I were that good at something, I would want to be fully recognized for it, but his size is just such a limitation.
Further, I don't think Bradley will get benched and I'd much rather have Smart get a lot of minutes and get some reps in. Plus, Isaiah is 5'9. I just don't see it working and I don't know why we would invest resources to add a player just because.