You wouldn't feel that way if they "fished" your children out of deadly floodwaters. Every single quote I have seen, from every single situation, in every country, the people protected were happy to have their help. Every. Single. One.
You can say they have been discredited, but I am yet to see a single complaint from anyone protected by them, ever.
And no, the Iraq government kicking them out does not count. There are a multitude of political reasons for that and besides, blackwater was (and is) not there to protect the Iraq government. They are not paid by the Iraq government.
Show me one customer complaint before you declare them discredited. Show me one conviction. Show me anything (except your own personal and hysterical assessment of the company's power) that reflects poorly on the company.
Let's, for a moment, assume you had a perfectly accredited security company without any flaw or accusations whatsoever... Would it be ok for authorities to hire them in a disaster? Or are governments not allowed to hire anyone?
Is it blackwater in particular, or do you not want any private security hired, whatever the extenuating circumstance, ever, for disaster relief? Are you saying that we shoud ban private companies from government security contracts in disaster relief, no matter what?
If you do think that it might be ok for the government to hire a private security company, under some circumstances, in particular situations, during a disaster, just maybe... then what are your grounds for banning blackwater from bidding on those contracts?