My guess is because the remastered DVD copies (with the original titles of course) were make for home video and are in the hands of Warner Home Entertainment and not TCM.
It just ridiculous though, the companies are under the same umbrella!
I know, it's like how most remastered DVD prints of the classic Looney Tunes are not shown on CN and Boomerang airings (they only air some from the first volume of the Golden Collections, and from the Road Runner and Wile. E Coyote Super Stars DVD). Including those that were remastered with their original titles.