It remains a rigorous and statistically valid study. I wish they'd excluded the race-based portion of the study because it's so ideologically toxic, but their primary point was that society was becoming increasingly biased in favour of individuals with higher IQ or "G" quotients, and that this should concern us as it could lead to further wealth polarisation along this axis. At no point is the claim made that IQ is a measure of human worth, or a complete accounting of intelligence - just that this measurement seemed to be correlated with better life outcomes. I really wish they'd left the study at non-Hispanic whites because that's a pretty important observation and something we should consider as a society. E.g. if a perfect "meritocracy" were instantiated in terms of economic rewards, that would be far from ideal if it meant throwing everybody else to the wolves just because they're less economically productive in that model.