Besides that sox doesn´t add noise shaped dither to 192kHz material afaik.
That's a perfect example of a Straw man: Besides the argument may be true w.r.t. to the automatic dithering feature of the SoX command line tool, it is not true w.r.t to the FFSoX plug-in. If the respective check box is checked the dithering effect is added to the effects chain, otherwise not (regardless whether this is useful or not). There's no automatic dithering in FFSoX.
Edit: If the emphasis is on "noise shaped" than the argument seems to be valid. The following is from SoX's "dither.c":
static const filter_t filters[] = {
{44100, fir, 5, 210, lip44, Shape_lipshitz},
{46000, fir, 9, 276, fwe44, Shape_f_weighted},
{46000, fir, 9, 160, mew44, Shape_modified_e_weighted},
{46000, fir, 9, 321, iew44, Shape_improved_e_weighted},
{48000, iir, 4, 220, ges48, Shape_gesemann},
{44100, iir, 4, 230, ges44, Shape_gesemann},
{48000, fir, 16, 301, shi48, Shape_shibata},
{44100, fir, 20, 333, shi44, Shape_shibata},
{37800, fir, 16, 240, shi38, Shape_shibata},
{32000, fir, 20, 240/*TBD*/, shi32, Shape_shibata},
{22050, fir, 20, 240/*TBD*/, shi22, Shape_shibata},
{16000, fir, 20, 240/*TBD*/, shi16, Shape_shibata},
{11025, fir, 20, 240/*TBD*/, shi11, Shape_shibata},
{ 8000, fir, 20, 240/*TBD*/, shi08, Shape_shibata},
{48000, fir, 16, 250, shl48, Shape_low_shibata},
{44100, fir, 15, 250, shl44, Shape_low_shibata},
{44100, fir, 20, 383, shh44, Shape_high_shibata},
{ 0, fir, 0, 0, NULL, Shape_none},
};
If a particular sample rate doesn't fit into the map the request for noise shaping is ignored:
for (f = filters; f->len && (f->name != p->filter_name || fabs(effp->in_signal.rate - f->rate) / f->rate > .05); ++f); /* 5% leeway on frequency */
if (!f->len) {
p->alt_tpdf |= effp->in_signal.rate >= 22050;
if (!effp->flow)
lsx_warn("no `%s' filter is available for rate %g; using %s TPDF",
lsx_find_enum_value(p->filter_name, filter_names)->text,
effp->in_signal.rate, p->alt_tpdf? "sloped" : "plain");
}