Parser errors in arrow functions (2v10.90 Bangle emulator)

I mention C not because I think its decisions are especially defensible—with all due respect to the Bell Labs crew for what they accomplished, even at the time it seemed haphazard (given that the valiant example of Algol68 was already available!)—but because, for good or ill, the brackets, the operators, and the control syntax are all inherited from it, and one of my original bug reports was about the interaction of these three. Specifically, is there any justification, any non-arbitrariness, to suddenly treating the conditions in while loops as syntactically distinct from other control construct conditions, at odds with tradition, ECMA, naive expectation and (I strongly suspect) efficiency of implementation? Sorry, I can't see it.