Cannot you get a tax id as a non resident alien? I know that if you hold USA shares outside the USA you can get a tax Id by filling in the w-8 ben forms (to avoid double taxation on dividends)
Also, in our case, the problem will exist only if the beneficiary happens to be in the US at the time of these options vesting and liquidating due to a company sale/IPO. At that point, they can't make an 83b election so will end up paying much higher taxes.
The W-8BEN is the form used to established beneficial ownership of a foreign-destined payment. It can also be used by individuals to claim treaty benefits (such as avoiding double taxation). An SSN, ITIN, or foreign equivalent is required to be provided on the form.