That's also my thinking, the seat's to the stage of readiness that it could be a suitable new 'flagship business class' that's entirely appropriate to the aircraft and the route, plus as you say serves for gathering feedback on any later tweaks.

Only issue as I flagged earlier might be different cabin width between the 777X and A350 - the aisles in the A350ULR already struck me as a tad tight. But the 777X seat could have been designed with the narrower A350 floorplan in mind, or it might be modifiable for those slightly tighter confines, or even – and this might be well beyond the score of the refurb – the newer A350s are being fitted with new sidewall panels that are more vertical and have a more advanced insulation material behind them that's thinner but still equal in attributes such as noise retardation. (I've seen the original and new panels aide by side on the A350 demonstrator).

This is the design that makes the A350 cabin a bit wider, approx 10cm, for airlines that want to squeeze an extra seat into economy (yikes!) while also narrowing the aisles. Anyway, and again I'm unsure of the 'scope' of the refurb, but if SQ went down this path it'd gain a bit of extra usable cabin width for the 777X business class suites, although of course it'd be a very expensive part of the upgrade... so not saying it'll happen, just adding this bit of into into the mix.