The DHS / Department of Justice have proven that US domains are not particularly safe or immune from arbitrary shutdown either.
That's true, but you're using false dichotomy - safe or not.
This is an issue of percentages. Technically, the United States might turn into a dictatorship overnight and choose to disconnect from the Internet, or be conquered, or a lot of other things might happen (most of which are less radical; the DOD orders a takedown of your domain, for example).
But it's pretty clear (to me at least) that buying a .com means you're much more likely to not have any issues, than buying a .ly. And if a registrar has just gone down, taking thousands of domain names with it, I'll be right - .com's will be statistically more stable.
Of course, here in April 2011 now we know that the risk was there all along. And now, any sane / rational business owner should think twice / again about registering a .LY domain.
But given that 12 months ago, the above statement that a .LY represented a substantially higher risk than a .COM would have been laughed at. Who would have thought that there would be civil war in Libya in 2009 or 2010? If you did, then maybe a job in political science awaits you.
Now their plan seems to be to distribute amongst many domains (having used j.mp a lot recently) so there's no single point of failure and that seems to be working as well.
Bit.ly's a unique case though, and doesn't represent the fad of taking .ly domains because it turns your company name into an adverb.