There is no squiggle that I can not hypothesize some way of using in a text message. The question is more, is there already some existing demand for it, before you asked the question? To which the answer would seem to be "no".

That's a contingent answer. If you, say, set out to try to convince the world to use it that way, and created that demand, then by golly, that demand would exist at that point and the answer could change. But hypothesizing some possible text message that could use it isn't strong enough to argue for inclusion in the standard because every possible proposal passes that test.