I've looked around and haven't seen it -- but thought I'd ask just in case.
Can we inject into the menu that comes up with we right click a player portrait? E.g. where we right click and say whisper/inspect/etc, and we right click and add a command for our own addon in there generally that would be supported by unitframes in general?
You can do it, but you should not. (You think you do, but you don't.)
You simply just can't eliminate the taint issues, and it will blame the whole world about who caused the taint, then it'll spread into queue/glyph/talent/toy/world marker dropdowns and you won't be able to use any of them.