If it ends up being ruled that Amazon infringed on Elastic's trademark (their case here is pretty flimsy) or copied Elastic's proprietary code then Amazon deserves to get raked over the coals for copyright infringement.

But Amazon offering hosted Elasticsearch and forking the project is something that I think is okay. It sucks for Elastic but it's good for customers. Amazon is driving the cost of hosted Elasticsearch down closer to its real costs which will always out-compete Elastic who's trying to use their margin to fund development as well. So many businesses fall into the trap of not charging for their actual value and get eaten when someone else is better at their paid complementary services. Elastic's value is the software, not their hosting abilities.