> pedantry around the definition of Open Source, which I understand ... it's close enough if you squint
Then I think that while you might have read and understood the definition, you seem to have missed the broader idea behind it.
> pay to play seems more than fair
That's irrelevant. Sure it's fair, but it's fundamentally _not open source_.
It's not about gospel or having power over you. It's about communication and well established meanings. Calling a fish a bird doesn't make it a bird, and resisting attempts by others to redefine the language I use is a Good Thing as far as I'm concerned.
(To their credit, Timescale uses the terminology correctly and I greatly appreciate that. I also think they picked the right licensing model given how things seem to work these days.)