If you ever hit an issue with Kafka or Strimzi, go to their Slack, some of the most intelligent people I've ever had the privilege to work alongside will be there, helping you.
I would prefer to say "free of charge", because that support is not actually free, it has a cost, you're just not required to pay for it.
But you as well as I know, that what the other participant in this conversation means, is that if a for-profit entity relies on support that is "free of charge" in this way, such that it can continue to profit on the back of their product support, then the for-profit entity really ought to seriously consider a voluntary donation of some kind to support the continued maintenance and support of the product.
And while that's super awesome that someone feels passionately enough about a piece of tech - that they're willing to spend their precious resources helping others... that kind of charity is untenable. You can't expect that person to be there at 3am when systems are down and your nightly processing jobs are failing.
For 0 money. That kinda free.