He comes to the USA to do some installation work of the product that was developed by his team in his country. How is this at all a sane idea that he now needs to be paid something entirely different based on the country where he is doing installation rather than what his actual salary is back in the country where he was hired and where he has his actual job?
Speaking as someone who moves around the world to operate software, train users and install and maintain equipment which my company develops here in the UK, no, I don't expect my pay rate to vary much from one country to another. There are local variations (dislocation pay rates if I'm more than 2 time zones away from home, which makes contacting the wife harder ; hardship rates for when working in disease-ridden hell holes with a good chance of being killed on the way to work ; overtime rates for more than 40 days a quarter away from home) which add up to about a 30% variation in pay rate from one job to the next.
There are, however plenty of employers in this business who do deliberately hire from the cheapest countries they can, and pay discriminatorily low pay rates as they move those staff around the world. We do try to harm them, our competitors, by hiring their best staff on UK contracts. If that means that we pay them like local maharajahs, we don't care. We still hire them out at UK rates, and shipping them around the world is a negligible cost (compared to finding the right people. Why should we care which continent they live on? That would be as discriminatory as hiring a Brit and paying him on a Thai rate just because he live there with his Thai family, even if he's working in Angola.
IF the company in question is based in India and this is what they're doing, then there's no problem with that. If the company is HQ'd elsewhere, then that's the rates they should be paying their staff on.
(Incidentally, our typical working day is 16 hours for seniors, 12 hours for juniors ; that's 112 and 84 hours per week respectively ; obviously in a crisis, you do what's necessary to not die, but generally that's not more than a few days of overtime.)