While he's currently a CS prof, he used to be a statistics prof, and it shows. He uses hard data properly analyzed
As an immigrant and someone who does data analytics professionally, I have to say: his analysis is logically, statistically, economically, and legally unsound. (Note that his report hasn't even been peer reviewed.)
It is logically unsound because, among other things, it starts with the premise that for the H-1b program to be desirable or economically valid, its workers should be, on average, "better and brighter" than US workers (a straw man), and because it uses arbitrary and unvalidated measures of quality.
It is statistically unsound because he infers that foreign workers are "less bright" than American workers because the "foreign" attribute correlates negatively with measures such as salaries and number of patents; however, it is easy to construct scenarios for which such negative correlations exist even if the workers are objectively still "brighter" than US workers. Inferring that populations of foreign workers are "less bright" based on his statistical analysis is incorrect.
It is economically unsound because he keeps arguing in terms of a "labor shortage"; while such a fuzzy term is often being used to justify H-1b visas politically, it makes little sense as the basis of an economic argument either way. And if one wanted to argue in terms of a "labor shortage", a labor shortage for low-skilled tech workers would be as important economically as a shortage of "the best and the brightest".
Matloff also argues for trying to create an artificial scarcity of workers in his profession by restricting admission of foreign workers. This has a long history in economics. Its effect is to benefit members of that profession, while making everybody else economically worse off. But if H-1b workers do the same work as Americans at a lower salary and free the best and brightest Americans to work in higher paid professions, that is a good thing from an economic point of view and for the wealth of the nation.
Finally, legally, he postulates the existence of "green card indenture", but in practice both H-1b and green card workers frequently experience only brief periods where they can't change employers.
And if Matloff (and let's not beat around the bush, "ebno-10eb" is Matloff) claims having been a statistics professor as credentials in order to lend weight to his arguments, the inference from that is not that his argument is stronger, but that he must have been a pretty poor professor of statistics.
There is some common ground is that if we limit immigration at all, we should limit it to those most valuable to the economy. One way of doing that would be to simply auction off a fixed quota of employment-based H-1b and green card slots to the highest bidders each year. That way, we don't need to get into silly debates as to who is needed, or who is not getting paid enough, and people like Matloff don't get to abuse the immigration system to achieve higher salaries for their preferred profession.
