For countries that aren't on the US' shit list (e.g. Brazil, South Africa, Saudi Arabia, or Thailand), why would I take a chance on Chinese legal agreements instead of American ones?

The American private company might be prohibited from launching military assets for you, but once a launch contract is otherwise signed, you know it's going to happen.

In contrast, a Chinese legal agreement is worth what, if the central government decides to get involved?

American Gov is far, far more fickle and likely to "get involved" / abuse export controls / fuck over friendlies due to domestic politics. Space is ITAR heavy, there's less guarantee that private American company can honor agreement than CCP verbal contract. This is 2024, JP steel just happened, US "rule of law" means nothing when strategic interests involved, never have. Can't say the same about PRC, granted they're to high end capabilities export. Ultimately, going with PRC likely will get you ITAR tier tech access bundled with cheaper launch, see state of military drones sales.