They'll have to base their service off the last Apache-2 version of Elasticsearch. Unrelated to this license change, but they'll probably have to rename it, too, after the trademark infringement suit finishes.
Edit: fixed typo
The license is plain vague.
And it's ES that's forcing AWS to do this.
Anyway I agree that the license is too generic and can use some more details but IMO it should basically cover all the automatism you explicitly create to manage the software you are selling access to. I mean, there is no need to publish the secret sauce for EC2 because it exists anyway and it's publicly available anyway.
To sum it up, I'm not against the spirit of the license but I agree the implementation should be better.