If bailouts are front-ended and funded through G-secs then at least US gets more money/treasury than it will at a later date. After the world discovers that US is going to default - no one is going to be ready to buy the treasuries and their prices will fall through the floor.
So in effect, Us will already have all the money they need to actually bailout the companies BEFORE investors panic. And then even if the world shuts its doors to US treasuries - so be it!
Its not unfair - but it is just saving your own skin!