Paramount are perfectly entitled to reuse material from their own franchise. Meyer was a hired gun, he does not own his script for STII.
Not to drag this off sideways, but they might very well have had to compensate him, even though he's not credited as a writer for the movie. Hard to tell since much of the dialogue is similar but switched between characters. Similarly, since Khan was a character created by another, there were almost certainly payments to the writers of "Space Seed". It's all part of the WGA contract.
Perhaps they would have to compensate him in line with union rules, but that does not make it in any way an equivalent situation to what is being tallked about here as JarodRussell is suggesting.
His example is completely inappropriate to the discussion, since Star Trek is Paramount's own entity. They didn't rip anything off anybody, they were entitled to do what they did. If that is indeed what Cameron has done, although I make no comment on that as I wasn't there.