The point I was referring to was S&S's ability to reprint the Bantam and/or Ballantine adaptations, not whether Penguin Putnam (successor to both Bantam and Ballantine) could prevent S&S from publishing OTHER Star Trek titles. Which, clearly, they cannot -- as the last 40 years demonstrate.
Can S&S reprint the Blish/Lawrence/Lawrence and Foster adaptations? Well, first they would have to want to -- they would have to see it as something that would make money. Then they would have to negotiate the rights with Penguin Putnam, which is apparently the largest publisher on the planet. So, I put the prospect way, WAY over into the "unlikely" category.
I suppose it's possible PP could issue ebooks of that material. But the fact they haven't suggests they either can't, or don't want to.