“... establish residency and line up an American university” and apply for his parents to immigrate under family reunification. Then, when they get here, they can bring the grandparents and enroll them in SSI.
The ultimate score (as you say) is bringing in their elderly parents (grandparents) who have never worked a day in America but get to glom onto SSDI and free medical and subsidized housing. Though often the grandparent is living in the household and the SSDI check goes into the kitty for all to share. Chinese and Asians have been parlaying this scam for decades
Go the ChinaTown in Manhattan someday for some good food. Walk around and you will see a bloc of tall apartment towers full of elderly Chinese in Federally subsidized housing. Half of them have no work history in the US