Once you violate the rules of the forum that may harm the forum and its users you are going to get banned, your trust rating will not cause you to lose your account from the ban, unless it is hacked.

These are the things that you cannot do if you have a bad trust rating, you cannot join a signature campaign, you cannot ask for a loan, people will not trust you when you offer services or products.

And these are the things that you can still do even if you have a bad trust rating, you can still join the discussion, you can open a new discussion and you can still open a new discussion and you can also receive merits.

If you're banned you cannot do anything.