He could get a visitor visa, which can be used for tourism and business. Even if you're from a Third World country, it's not that hard to get it. Then the US e

He could get a visitor visa, which can be used for tourism and business. Even if you're from a Third World country, it's not that hard to get it. Then the US entity would pay his company in Netherlands, and he would get paid in Netherlands from the Dutch company. The situation is the same as if you're a manager from a foreign company having a business meeting in US.