As far as I know, Garuda does not currently fly to the US, nor does it operate any codeshares with Delta. (All the codeshares are operated by Delta).
I.e., Garuda sells seats on Delta-operated flights to/from the US (between Haneda and LAX/SEA), but Delta does not sell seats on Garuda-operated flights.
Garuda is keen to resume flights from Jakarta to Los Angeles on Boeing equipment, so Boeing is a key partner in getting Indonesia back to Category I status.
Thai Airways is a Star Alliance member, and as GlobalNav mentioned, under the rules Thai can keep flying to the US and keep its existing codeshares, but Thai may not expand services to/from the US.