Could the company not just issue a hundred trillion dollars of it in a day and sink the currency if they wanted to (or were forced into it).

There's no built-in way to verify that minted Tether can be verified to be backed. If there were, firstly there'd be no questions about the backing at all, it's all public on the blockchain, and second, it would revolutionary and actually useful to have a smart contract that can track real assets and not let them vanish from under it.

How were multiple validators coordinated to switch the chain off?

When we say Putin can press the red button obviously we don't mean a physical red button pressed by Putin himself. But he is the one coordinating.

There's many channels/groups where the validators coordinate and communicate for all kinds of chain related activities, tasks, upgrades, etc.

Actually, the Putin analogy is basically exactly what happens. Putin pushed the "red button" and everything else is a direct consequence.

That's not how it works with validator based PoS chains. Absolutely Kwon can "suggest" to do something, but has no omnipotent influence or control unlike your Putin analogy.

Validators are absolutely free to discuss, debate, and agree to whatever they think is best. Additionally, the validators in the active set with this power are put there mostly by the community of token holders.