Pretty sure this isn't a bug, it's a misfeature, although I'm not entirely sure how useful it is since you can't toggle booleans in variable and list watchers (which would make sense).
Yeah, I agree that it doesn't make much sense to toggle a speech balloon. (It's definitely not intended to change the variable value, since speech balloons don't necessarily represent variables!) Doesn't seem like a high priority though.
The only issue is that the toggling in the speech balloon might appear to the user as if it were promising to change some actual program data, especially if (as in the OP) the speech balloon came from an orange variable oval. Not a bug, just awkward.