For direct, real-time emergency information this is simply a bad idea for the reasons we have mentioned here as a group. This purchased space is in the "advertisement" area of the search and a great deal of people have already trained themselves to look past it. Even more important a lot of companies now make google chrome extensions and/or applications for browsers that disable adverts from the viewing area as most have already agreed they take up space and don't provide value 99% of the time. This is a very difficult human factor to over come.
Additionally, why should the government pay for "critical online placement" for actual emergency information? (Technically they get it for free via the EAS, etc.) Also, as stated, SEO replaces the need for paid placement, especially when coupled with the standard media barrage PIOs make before and after disasters announcing where the websties, blogs, twitter, etc are available.
I mean, we need to think about the context here: near real-time information. Not preparedness, etc. For static preparedness, programs, etc PSAs and adverting is key. Very different from actual emergency comms.