Yeah, you've said that before (I think when we were having a discussion about whether Duning was the only TOS composer to borrow from the other composers). I'm not sure I buy it.
The theme for Spock's scenes with the Commander is heard mainly in "Vulcanization" and "Back From Dead / Commandeered" (s3d3 tracks 6 & 10). They don't sound anything like Steiner's "Marlena" cues (s2d3 22-24-25), certainly not rhythmically and they may not even be the same key. (I can't tell about the intervals. My ear for intervals is, to put it kindly, "untrained").
I never claimed they were the same melody or rhythm; obviously they aren't. I'm saying Courage's Commander motif is structurally similar enough to Steiner's "Romulan Theme" that it seems likely to be a pastiche of it, an homage to it. Much like Steiner's Enterprise
theme from "Charlie X" and "Mudd's Women" is a pastiche or inversion of the Courage fanfare -- different notes and timing but the same structure, not a variation on the theme but a reference to it.