Honestly, there is no reason this lawsuit should be pressed. As you pointed out I'm sure there were visa's required for some applicants, and 20% Asian is still good by percentage.
Also, I find it interesting how national average always seems to justify discrimination against Asians when it comes to jobs/college acceptance but then if someone brings up how Asians can be under-represented in things like media representation or politics, some people will say it's because there aren't many Asians who go into acting/modeling/politics.
If the ratio of those hired matches the ratio of applicants how does anyone make a complaint of discrimination?
No it's not. It's in fact the opposite. Sexism is systemic to the point where you're lucky to have 5% of your applicants be female.
There are real differences there between sexes, and those preferences affect what career is the best for you. You don't pick whats average for you, you pick your best career with all things considered, and small differences in preferences can skew the outcomes heavily. Also I like to point out there is bunch of careers where there is heavy shortage of MEN choosing it for same reasons.
They'd complain that the company wasn't doing enough to attract resumes from underrepresented groups. That's the usual thing, anyway.
It does smell like revenge, especially given that the numbers are so unusual and the company is probably dealing with security clearance issues. The fact that the numbers are so strange in the supposed pool should raise lots of red flags about one particular country too: were these people with family connections to China? That is normally disqualifying. Is the company expected to hire people who are certain to fail the clearance process, and then get stuck firing them for that failure?