That is totally fair according to the license used, even I don't find anything bad with it. Rather its a good portfolio item for oss developer.
Next thing which developer can do is, check if amazon is up-streaming new updates and bugfixes to their product, are they contributing to the existing open issues for bug-fixing,if yes that's win-win for both.
if you are planning to leverage the project for commercial product, I would suggest future dual-licensing clause which is like "Any contribution to the project will be licensed under AGPL, and XYZ LLP will get its copy as a full ownership with WTFPL license exclusively". Add an enterprise plan for your product where big corps can purchase its code license directly from you for fair price to get it under GPL/Apache license.
just my 2 cents.
Next thing which developer can do is, check if amazon is up-streaming new updates and bugfixes to their product, are they contributing to the existing open issues for bug-fixing,if yes that's win-win for both.
if you are planning to leverage the project for commercial product, I would suggest future dual-licensing clause which is like "Any contribution to the project will be licensed under AGPL, and XYZ LLP will get its copy as a full ownership with WTFPL license exclusively". Add an enterprise plan for your product where big corps can purchase its code license directly from you for fair price to get it under GPL/Apache license. just my 2 cents.