I have seen J award availability on 772 flights too (i.e. PVG-SIN) but that's SQ's old J regional product, so of course their seats aren't as nice in comparison.
Not to divert topics here, but does anyone know if SQ is similar to LH and LX where they release award availability for UA 1-2 weeks before departure date? Or does SQ prohibits long haul F & J award for UA customers?