Hmm... the way to figure out HOW to copy and paste something on the mutli-touch screen is probably the issue here. Like someone said, it probably just needs a new, unique finger gesture that's different enough from the other ones.
What about just using two fingers -- one, to just press down somewhere (as if to "hold" the screen in place), and then the other finger wipes over the text to be highlighted? I don't think that gesture has been used, yet. Then once you have something highlighted, releasing the screen with both fingers brings up a window with buttons to "copy" (to clipboard), "cut" (if you want to delete the text) or "cancel" (if you made a mistake).
For larger bodies of text, perhaps a three-finger press on the screen could be the equivalent of a right-click, bringing up a window with the above buttons, and also "select all," "paste," and other functions. If you do this, and you select "paste," a temporary cursor pops up, which you must drag to the point where you want to paste, and lifting your finger up adds the text at that spot.
Or maybe there's a less complicated way of doing all that.... 😉