@Randy ******
(please exchange "he" with "you") . . . While for the application to the 90-days Non-Imm-O Marriage Visa outside of Thailand, the required 400,000 THB can sit in ANY bank account ANYWHERE in the World as long as he can prove the account is in his sole name,
The 2 months seasoning of the 400,000 THB in a Thai bank account is the official requirement for the application to the 1-year Extension of the Stay Permit Based on Marriage to a Thai Wife, but sadly, some Immigrations want to see a 3-months seasoning.
These Immigrations seek to drive the applicants into the fangs of agents and pay tea money, because they know you just can't fulfill this 3-month requirement on a 90-days Non-Imm-O marriage visa.
He has another, very viable option:
He can buy more time by applying to the 60-days "family visit" extension near the expiry date of the 90 days out of the Non-O visa.
However, to be able to apply for the 60-days extension, he needs a freshly printed Kor Ror 22 or 2 (whichever applies) from an Amphoe to show Immigration that his marriage to a Thai is registered inside Thailand