There is no problem, assuming that one believes that the list-of-USV abstraction (i.e. sanitising strings to be valid unicode) is the right thing to enforce at the component boundary, _including_ when the internals of the component are implemented using JavaScript.

I appreciate that this is exactly the point where we currently disagree, and accept that I won't be able to convince you here. However, the AS website's announcement did not make the boundaries of the debate clear.