CBS isn't the problem. "Star Trek's" popularity is the problem.
Trek doesn't draw audiences of sufficient size or the desired demographic to make it viable on anything other than a niche channel like SCIFI right now.
But this always leads to the question of why Star Trek has to have HUGE numbers or nothing at all. The expectation level seems to be set to high. A new series could get good numbers but that does not seem to be good enough for CBS they need mega numbers or nothing at all. Right now CBS as led by Moonves has no interest whatsoever in a Star Trek show.