"Somewhere" was wrong. Here's the catch though. Landlords are self employed, so you must take a look at the "total income" line of the latest (all three but latest is critical) and see if that number qualifies. "He" does not have his wife's income, but it can be used with her being the joint sponsor's household member, combining income.
The big issues with many landlords is they take big legal deductions that decrease their rental income, often to a negative number. That negative number reduces the total income on the return. The combined income is what you see on the total income line, plus the social security. If you see any reference to the SS on the tax return, its ok but gets a little more complicated.
What is the relationship between the joint sponsor and his wife, and the petitioner, and/or beneficiary? This is also considered.