It does seem tricky. On on hand, they want to stop AWS using "Elasticsearch" in a product name because it isn't in partnership with Elastic co., but on the other hand AWS's product really does contain Elasticsearch, which is why they are changing their license. If AWS had a product called "Elasticsearch Service" which didn't contain Elasticsearch, then it would be pretty clear cut as that would be very confusing, but a product called "Elasticsearch Service" that really does contain "Elasticsearch" seems pretty self-explanatory.