Not necessarily true. If he comes from a country with a significantly different culture (i.e., somewhere other than Europe), he would probably be more comfortable marrying someone of his own nationality who is also a recent immigrant, and thus is more likely to also be a non-citizen.
Unless there is some other point to this comment that is going WAY above my head.
Background: I'm a citizen, and my wife when through the process when we got married six years ago. She became a citizen a couple of years ago.
Also, if you get divorce after getting green card and if USCIS finds out that you married citizen only to get green card, they can revoke it.
But the unqualified "no leverage" of the OP seemed to imply at least to me that they thought that the green card would be taken away in a divorce irrespective of number of years of marriage (it doesn't after two years unless you got into a fraudulent marriage).
And I do not think the GP suggested getting a sham marriage. Yes, if you really enter into a sham marriage then the "wife" will have lots of leverage over you.