Setting timeZone to null does not have any effect

[stri8ed]

In the documentation, its stated:

Sets time zone. If you want to use user's computer time zone, pass null

However the code which implements this, will always cast the null into "UTC".
Config.prototype._timeZone = function(val) { return ko.observable(val || 'UTC'); }

So passing null does not have the desired effect, and instead its reverted to UTC.