Yes but how does changing their license affect a trademark? If they are legally in the right and this is a violation of their trademark they should win their lawsuit about it regardless.

Also my initial question was not purely rhetorical, I would assume "Linux" is also trademarked so I'm wondering what is the difference there and why Redhat selling RHEL has not been the same problem.

Because Linus has no problems with Red Hat? And because Red Hat employs a lot of the key contributors to the Linux kernel?

Also: https://www.infoworld.com/article/2671387/linus-gets-tough-o...

I don't think Redhat could have built their whole business on the just the implied understanding that Linus is cool with it. I'm more talking about the trademark issue, did they legally get the right to use the Linux trademark in some way that Amazon Elasticsearch didn't? Just curious if there is any substance to what Elastic is claiming here or if it's purely a PR stunt.

Edit: based on the Linux Foundation link in another comment, it seems they have a clear process for sublicensing the trademark. So I guess Elastic is claiming AWS just launched their ES service without their legal team ever having bothered looking into the trademark? That seems very strange for such a large company.

See https://www.linuxfoundation.org/the-linux-mark/

I think it's not the same problem because Red Hat contributes heavily back to Linux kernel

I think they'll lose the trademark case.