I think he is claiming that immigrants are accepting jobs that they wouldn't otherwise accept without the possibility of obtaining a green card (or are willing to accept such jobs at substantially lower pay than they would otherwise agree to without the green card benefit). However, no evidence has been provided to substantiate the claim.
I've read that about 3% of H-1B holders actually try to get a green card while the rest do their time here and then go back home with their new skills.
But they did productive work while they were here.
Our experience is a little better than that but certainly the majority of the H1B1 visa holders don't get a green card and don't move here permanently.
I would say that about 20% do stay, but these by and large are Germans, who are more senior or Canadians for whom the US isn't all different than Canada, just warmer all year around.
We have only had one Chinese stay permanently, he and his wife, who is also an engineer now are US citizens and they have one child who only dimly remembers the China he left as a five year old. He is now as American as my son is and will graduate from Medical school this year. He got his citizenship the very earliest that he could. When he turned 18 I think.
We have one Brazilian here who was on a H1B1 visa. She speaks five languages really well and can muddle around in three more. She came to work for us because we could get her a visa, her previous employer CNN, couldn't get her one, they had all of them that they could get. An extremely intelligent woman she learned the business from translating and she is now handling much of our business in South America. She is now married to a Georgia good old boy and has a three year old daughter who currently speaks three different languages.
Since she married an American citizen she no longer needed the visa to stay and work in the US. After nearly two years she has finally gotten her application for full citizenship approved. The INS (or so ever it is called this week,) suspected that hers was a marriage of convenience to get her citizenship, which it wasn't. Admittedly they didn't help their case since in six years they got divorced twice and remarried twice in addition to the original marriage. It is a thing that they do. They kept living together even when they were divorced, in fact, that is when she got pregnant.
We have three Indians here on the H1B1 visas with their families. I don't think that any of the three will make it here. All three for the same reason, their wives are unhappy here. The wives of H1B1 visa holders can't work. Most of them did work in India.
We have a Venezuelan here with a Columbian wife who has two small children. They probably will make it to getting their green card because the wife is concentrating on her children, she speaks excellent English, has a large number of American friends and won't want to work until her children are in school. By then they will have their green cards and she will be able to work.
We have an Argentinian who worked for me eight years ago on site in LaSalle, Illinois. He was single then, working for a consulting engineer who did our structural design out of St. Louis. After my project was finished he went back to Argentina. He had been here on a regular business visa that had expired. He worked in Argentina for a company there for two years. He got married to an Argentinian woman during this time and they had a daughter. He decided that he wanted to come back to the US and called me. We hired him in Argentina and put him to work on a site in Brazil and started applying for a H1B1 visa for him. It was really hard to get one for him because he had been in the US on a regular business visa working for another company. It appeared that we had hired him just to get him the visa. After more than six months of trying we finally got the visa.
It is really touch and go if they will stay. Left up to him and they would. But his wife was a clinical physiologist in Argentina. And as I said she can't work in the US. Even if she gets a green card I would imagine that she would have an extreme number of hoops to jump through before she could practice in the US. Besides she is not working very hard hard to learn English.
It is a hard thing to move to a different country. I have lived for extended times in other countries, three to four years each but I never moved my family and the moves always were temporary. My son and my daughter did at different times stay with me in Germany and China, going to school. My young family with no one of the children in school lived with me for a time in Montreal, but they couldn't handle the winters.