Well, according to what Mohan posted, if he goes to the IRS website and take the survey at
https://www.irs.gov/help/ita/am-i-eligible-to-apply-for-an-individual-taxpayer-identification-number
It will tell him that he is not eligible for an ITIN. According to
https://www.irs.gov/businesses/small-businesses-self-employed/responsible-parties-and-nominees
only a Responsible Party may apply for an EIN. A responsible party is an individual with either a SSN (he is not a US Citizen), an ITIN (according to the above survey, he does not qualify), or an EIN (you can't get an EIN unless you have one of the other two). If he is trying to form a business within the U.S., or open a U.S. bank account, that is when he will need an EIN, and he would need a Third-Party Designee to file for an EIN.
So, those are the IRS sources I'm quoting from, which seems clear to me. Perhaps I'm reading all of this wrong? I could not find any IRS source stating that a foreign entity could not sell to US customers unless that entity was registered as a business in this country.
Of course, I would always recommend he speak with a business attorney since it is obvious that we are all reading the IRS guidelines differently. On that note, Stewart Patton, a U.S. tax attorney who specializes in foreign entity taxes, said that the only time a foreigner needs to pay U.S. taxes ( which is the only reason to get an EIN) is if that entity has Nexus within the U.S., which means that Mohan needs an EIN if he has a business office, distribution center, warehouse, U.S. employees, etc. here in the U.S.
Stewart also said that just because you sell a product to people in the U.S. does not mean you need an EIN.
Tomas