A customer is doing a full migration to the cloud. They're already using FLOSS project X on-prem and asks 'Hey, <cloud vendor>, project X is a super important part of our environment? We can't move forward unless you support it. Also, can you manage this for me? I'd really prefer not to roll my own servers.'
What would YOU, as the cloud vendor, do? Give up the on the business (both upfront migration costs and down line usage and maintenance costs), or legally exercise the license that project X's creator CHOSE?
Also, consider that, at your scale (you being the cloud vendor), if 1 customer is having this issue, it's impacting tens if not hundreds of others.
As someone who works for AWS and fields feature requests from customers constantly, the above situation very common.
Is there really a difference at all? You're complaining that a managed service is somehow "a direct competitor". Compete in what? I mean, am I really competing with the project if I get a few instances up and running?
By your line of reasoning, they are actually helping the project grow and establish itself as relevant piece of infrastructure. Somehow I don't see this being used as a justification to demand a share of the revenue the other way around.
In the end, all I see is people complaining that someone who uses a project that was always freely distributed happens to have deep wallets, and somehow hey feel entitled to some cash just because a third party is rich. Where does this make any sense?
There isn't a legal difference in AWS repackaging an OSS project, and a company using it internally, but there is a difference in terms of the end result of how the project develops.
That's why I've seen that most comments is support of AWS are either ideologues or their livelyhood depends on a large company that's doing this.