Got the same email from TD Ameritrade. Went to TD Ameritrade Asia FAQ page. Item number 5:

May non-Singapore citizens trade with TD Ameritrade Asia?
Yes, non-Singapore citizens may register with TD Ameritrade Asia, provided you are a Permanent Resident or have a valid Employment Pass or Work Pass. You will be required to provide us with a valid Tax ID number in Singapore to open the account. You will also be required to verify your Singapore address by providing us with a copy of a utility bill and/or bank statement listing your address.

Anyway I've sent them a message asking them about those without an SG Tax ID.

Will do, will let you know when I receive their reply.

Yup I get what you're saying. If there's no way around what's stated in the FAQ then yeah, they are likely dropping Malaysians and perhaps quite a few more accounts throughout some Asian countries. With that requirement, it would likely mean that TDA Asia does not handle that many accounts.

TDA Asia just told me that they will accept Malaysia accounts. So good news for those who want to transfer or open one.

Just check out their fees. It is different from TDA Inc.

Those who transfer get to keep their existing fee structure though.