Earlier quoted context omitted.
AGPL doesn't protect the Free Software business. It protects the Free Software code itself. The fact that a company backing an AGPL-licensed work goes under isn't the direct concern of the license. The fact that the code itself remains as Free Software, with a source-release obligation, even when run as an online service, is the principle concern. Copyleft free software licenses, as with the GPL and AGPL, promote the…
You're right, but there's another concern: who maintains the software? The original developers forming a company that supports development is not possible if the company is not protected by the license in some way.
Under the AGPL, the source-disclosure provision persists.
In both cases, Amazon is doing software development, but in the first, they're not contributing back to the codebase. In the second, they are.
Amazon are maintaining the software. Along with other users.