the IRS instructions are as follows
In the case of a disregarded entity (DE), the partnership will enter the TIN of the beneficial owner of the DE in item E and the beneficial owner's address in item F.
the sole proprietorships are DEs
the beneficial owner of the DE is the sole proprietor
so turbotax is following IRS instructions and requiring an SSN. there is no way around this if you want to efile.
I don't know what the IRS position would be if you paper filed using the EINs and name of the sole proprietorships
