They knew what they were doing. They released OSS to build traction and a community. In some cases, the community contributed quite a lot to the quality of the software - even if not a lot of code. It never would have gained any traction or interest from enterprise buyers without that. Then that valuable software they had already given away was used to build a business that couldn’t create enough value on top of it.
The only people with any justification for hurt feelings are the community contributors.
AWS literally paid for developers for the redis project, including the salary of core members. It's not like they didn't contribute back to the community.
They pay for a lot more open source work than that as well, but they also don't get to make any special claims for doing that. None of it is charity - it is simply in the collective interest of a lot of tech companies to commoditize and share the costs of infrastructure software. Even shaming freeloaders is uncalled for and against the ethos of OSS, which is sort of implied in making your statement.
The only people with any justification for hurt feelings are the community contributors.