KrisFlyer is great and works very well with European and other Asian carriers. This appears to be a UA thing basically disabling all *A RTW not just Singapore. UA is definitely the weak link for that alliance, OneWorld may have some other weak links (South America) but UA is not just a weak link, compared to pretty much any non US airline is also terrible in its own right. Using American as a One World status holder is far superior to UA as a *A one.