Most of the revenue comes from the IP cores.
A common business model for companies like this is to enable developers to learn their tools cheaply, so that when they develop something for their employer, they're more likely to reach for those tools/ecosystems and have the employer pay for those tools.
This just cuts out beginner/hobbyist FPGA devs from using industry standard tooling.
So if they have to keep maintaining it and offer the basic tier for free on Linux... just why? It doesn't make any sense to me.
Maybe they receive "too many" bug reports from Linux users?