Where their revenue is made is irrelevant. What created the revenue IS relevant. If American-based ingenuity is still their moneymaker, then their hiring practices should reflect that.
Presumably IBM is well aware of the source of their "moneymaker". Probably far better than you and certainly better than me. Show me your evidence that US based talent would provide a better outcome (greater profits) to IBM than what they are doing. Frankly you are talking in unsupported hypothetical ideas rather than evidence based facts.
Furthermore where their revenue is made is very much a relevant consideration as is the location of the best talent to make it. IBM is a global company and has the resources to identify talent wherever it might come from. The notion that 5% of the world's population would constitute a disproportionate share of the talent pool is an irrational assumption unsupported by evidence and IBM is big enough to actually have that evidence. Also conveniently you also have neglected to consider costs which only a fool would ignore. The purpose of a company is to make profit, not revenue. You cannot consider profit without considering both revenue and costs. If they can get the same or similar outcomes with lower priced foreign talent, what possible justification is there for hiring overpriced US workers? What makes US workers such special snowflakes?
Look I get it that there are huge and real problems with stuff like H1B hires and the like but there is a reason that companies feel the pressure to do that sort of thing. US labor is among the most expensive in the world. Only a fool buys something more expensive if the performance doesn't justify the extra cost.